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your age will be three times his/her age

by Jesus
(Virginia )











































At some point during the lives of you and the youngest person, your age will be three times his/her age at that moment. Write an equation which models how old in years each of you will be when you are three times as old as the younger person. Explain the reasoning which helped you develop your equation. Solve the equation for your ages when you are three times as old as the youngest person. Are your answers reasonable?

The ages are 47, 30, 10.

I would like to also have reasoning behind the answers. I am here for help yes but I truly want to understand this for future knowledge.

Comments for your age will be three times his/her age

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Oct 08, 2012
three times his/her age
by: Staff


Answer:


Given the ages:

10 years old, 30 years old, 47 years old


Write an equation which models how old in years each of you will be when you are three times as old as the younger person.


Middle person’s age = 3 * (Younger person’s age)


x = middle person’s age


y = younger person’s age


x = 3 * y



Since the youngest person will always be 20 years younger than you


y = x - 20


Substitute x – 20 for y


x = 3 * y


x = 3 * (x - 20)


Solve for x
x = 3 * (x - 20)


x = (3 * x) - (3 * 20)

x = 3x - 60

x + 60 = 3x - 60 + 60

x + 60 = 3x + 0

x + 60 = 3x

x + 60 - x = 3x - x

x - x + 60 = 3x – x

0 + 60 = 3x - x

60 = 3x - x

60 = 2x

2x = 60

2x / 2 = 60 / 2

x * (2 / 2) = 60 / 2

x * (1) = 60 / 2

x = 60 / 2

x = 30


Substitute 30 for x in the original equation


x = 3 * y


30 = 3 * y


Solve for y
30 = 3 * y


3 * y = 30

3 * y / 3 = 30 / 3

y * (3 / 3) = 30 / 3

y * (1) = 30 / 3

y = 30 / 3

y = 10




when the middle person’s age = 30 (current age)

the younger person’s age will = 10 (current age)


and the older person’s age will = 47 (current age)


the middle person’s age = 3 x the younger person’s age




Thanks for writing.

Staff
www.solving-math-problems.com


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