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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

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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
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Nov 14, 2018
but why though NEW
by: Anonymous (TJ)

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

ITS 21

Sep 16, 2019
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by: your mom

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Oct 04, 2019
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Oct 22, 2019
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Nov 09, 2019
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Nov 09, 2019
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Nov 10, 2019
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Nov 12, 2019
Sum and difference NEW
by: Anonymous

Sum of 15 and their difference is 3

Dec 08, 2019
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Dec 21, 2019
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