# sum of two numbers is 15, and their difference is 7

by Denise
(New Orleans)

Linear Equations

The sum of two numbers is 15, and their difference is 7.

Write a system of linear equations and solve the resulting system.

Let x be the larger number and y be the smaller number.

How do you work out this problem?

### Comments for sum of two numbers is 15, and their difference is 7

 Jan 12, 2014 answer by: Anonymous x + y = 15 - x - y = 7 2y = 8 2y/2 = 8/2 y = 4 x + 4 = 15 x + 4 - 4 = 15 - 4 x = 11 check 11 + 4 = 15 15 = 15 11 - 4 = 7 7 = 7

 Feb 14, 2014 ANSWER TO DENISE QUESTION by: SIBONISO MDLALOSE 2X+Y=15 AND 2X-Y=7.NOW SOLVING FOR X AND Y SIMULTANEOUSLY.LET Y EQAUL TO 15-2X.THEREFORE 2X-Y=7 WE CAN WRITE IT AS 2X-(15-2X)=7;4X=22;X=11/2.AND Y WILL BE EQAUL TO 4.THEREFORE 2(11/2)+4=15 AND 2(11/2)-4=7.THIS SOLUTION PROVES THAT SUM OF 2NUMBERS IS 15,AND THEIR DIFFERENCE IS 7 ONLY IF X IS A LARGER NUMBER AND Y IS A SMALLER NUMBER.

 Mar 30, 2014 number word problem by: Staff Answer x = larger number y = smaller number x + y = 15 x - y = 7 use the elimination method to eliminate the y variable, and then solve for x add the two equations x + y = 15 x - y = 7 ------------------ 2x + 0 = 22 solve for x by dividing each side of the equation by 2 2x = 22 2x / 2 = 22 / 2 x = 11 substitute 11 for the value of x in the first equation, and then solve for y x + y = 15 11 + y = 15 subtract 11 from each side of the equation 11 - 11 + y = 15 - 11 0 + y = 4 y = 4 final answer: x = 11 y = 4 Thanks for writing. Staff www.solving-math-problems.com

 Dec 29, 2016 maths NEW by: ash this mind blowing

 Nov 14, 2018 but why though NEW by: Anonymous (TJ) what the frick this dosent help at fricking all!!!!!

 Apr 12, 2019 15 and 7}^ 9 NEW by: ur mum ITS 21

 Sep 16, 2019 creeper aw man NEW by: your mom this is high scool level math FRIK

 Oct 04, 2019 OMG NEW by: Anonymous THANK YOU:)

 Oct 22, 2019 HHEHEHE NEW by: Anonymous FUCK YOU

 Nov 09, 2019 what NEW by: Anonymous this totally worked!

 Nov 09, 2019 some people are mean NEW by: Anonymous i think this helped more than any other wibsite!

 Nov 10, 2019 UGH NEW by: Anonymous is mad OMG IM PLAYING PRODIGY AND THIS IS CONFUSING ME MORE THAN THE PROBLOM

 Nov 12, 2019 Sum and difference NEW by: Anonymous Sum of 15 and their difference is 3

 Dec 08, 2019 vomit NEW by: G This is shit, it didn't help at all!

 Dec 21, 2019 hhhhhh NEW by: Anonymous this is great

 Mar 03, 2020 playing prodighy NEW by: Anonymous omg i dont understand

 Mar 08, 2020 No way NEW by: Anonymous Just here to keep this comment thread still going, confirmed algebra is dumb.

 Mar 14, 2020 E NEW by: Anonymous NO ANSWER FUCK

 Mar 30, 2020 response NEW by: Anonymous probably 7

 Apr 01, 2020 whoever wrote that is a fucking dick NEW by: sakaue whoever made this is a fucking dick

 Apr 05, 2020 lmmmmmmmmmaaaaaaooooo NEW by: Anonymous lmaoooo i just love the comments thoooo

 Apr 08, 2020 Problem NEW by: luna this did not help it is the same as the other one i looked at! but thanks thow

 Apr 12, 2020 me NEW by: Anonymous the answer is 11 and 4

 May 01, 2020 Bich NEW by: Anonymous I just had sex

 May 11, 2020 PRODIGY ERROR NEW by: GAMERPRO77 I AM PLAYING PRODIGY ( too ) AND THIS IS TOOO CONFUSING! CAN YOU MAKE IT MORE UNDERSTANDABLE??!!

 May 12, 2020 explanation without using algebraic equations NEW by: Anonymous x + y = 15 tells you that the set of real numbers can range from 15 to 0. We already know 15 and 0 won't work because 15 - 0 = 15 (not 7). We need to adjust the 15 and 0 so the difference drops by 8 (the difference of 7 is 15-8). Half of that drop: 4 (8/2 =4) tells us how much to subtract from the greatest possible value (15) and add to the smallest greatest value (0) to decrease the difference between the 2 numbers by 8. Instead of 15 and 0, we now have 11 and 4. It might help to show the difference between 15 and 0, as well as 11 and 4 on a number line to visualize this. Hope that helps.

 May 12, 2020 iwouldntusethiswebsiteitsafakeandidontwannagethacked:) NEW by: yall are fake and hackers this is a fake website, otherwise you would be answering the question we are all asking, so frick u

 May 15, 2020 Mkay NEW by: Anonymous Im just looking for my math awnser :\

 Jun 02, 2020 i hate this NEW by: idfk i hate thissss

 Jun 03, 2020 creeper fuck up man NEW by: YOOOOOOOOOOOOOOO this is bad I HATE IT ITS SOOOOOOOOOOOOOOOOOO bad

 Aug 19, 2020 ask NEW by: Anonymous Awesome

 Aug 24, 2020 yo NEW by: Anonymous this is the worst

 Aug 24, 2020 <3 by: Anonymous thank you so much! helped a lot..people that are not understanding please read carefully :)

 Sep 01, 2020 on prodigy NEW by: Anonymous its 11 and 4

 Sep 02, 2020 can it be less copex? NEW by: Anonymous ??

 Sep 16, 2020 So out of topic NEW by: Siena Why can't you just let us see the actual numbers!!! I am plying prodigy and still this sight will not let me see the freakin answers!!!!this sight is soooooo stupid

 Sep 16, 2020 what is the answer!!!!! NEW by: Anonymous what?!?!?!!?

 Sep 22, 2020 I hate this NEW by: Anonymous THIS SHIT IS DUM WHO EVER CREATED THE IS A BiTCH

 Oct 07, 2020 Sucks Ass fake website by: Armani This is a fake website!!!!!!!!!Am playing prodigy and I keep getting it wrong!!!!!!!!!!!!! whoever made this sucks

 Oct 09, 2020 not true i am playing it i got it right bitch NEW by: Anonymous not true

 Oct 18, 2020 real answer to the question NEW by: Anonymous hello i will be answering the question my username on prodigy is damasterc and i've been trying and trying and i finally have it the answer is 11 and 4.

 Oct 21, 2020 Tik Tok Queen NEW by: Anonymous FUCK YOU

 Oct 25, 2020 Im confused NEW by: BTS lover POV: Your playing prodigy and looked this up xD

 Nov 13, 2020 blabla NEW by: Anonymous HTML

 Nov 24, 2020 idk NEW by: Anonymous idk

 Nov 30, 2020 Comment Title NEW by: Ash This helped me and i'm only in 4th grade

 Dec 14, 2020 ... by: Anonymous I have spent 1 hour and a half trying to find the answer. You now what frik it I give up

 Dec 15, 2020 sucks like pussy NEW by: bitch i'd RATHER SUCK A NASTY GIRLS PUSSY THAN GO ON THIS STINKY SHITY POOP WEBSIGHT

 Dec 17, 2020 huh NEW by: Anonymous when you playing prodigy and this makes no since ;-;

 Mar 31, 2021 BITCH I HOPE YOU SEE THIS NEW by: :yeetamon no FUCKING answer you dumb ass prick i was siting here for a GOD DAM HOUR STARING AT THE FUCK SCREEN TRYING TO SOLVE THIS FOR PRODIGY yes im under 10 :)

 Apr 21, 2021 bro NEW by: Kenneth The anwser is at the bottom idiots.

 May 24, 2021 dislike NEW by: ugh this not helpful.

 Aug 20, 2021 my son is mad NEW by: karen5544soccermom this is poopy no answer i want to speak to a manager :(:(:( dont go

 Oct 29, 2021 This is nothelpful NEW by: this is not helpful this is not helpful im trying to get the aswer fo prodigy and yes im 10