Asked by Wesley

Mack is 3 times as old as Justin. In 3 years, Mack's age will be 5 more years more than 2 times as old as Justin. How old are Mack and Justin?

What is the system of equation for this?
I got 3x=7 and x=5+2y. But it's wrong because, I ended up with negatives.
Help! Thx.

Answers

Answered by Reiny
First you have to define your variables.
your equations have no relation to the English sentences.

Let Justin's present age be x
then Mack's present age is 3x , (no need to use 2 variables)

In 3 years time:
Justin will be x+3
Mack will be 3x+3

now translate the English into math
"Mack's age will be 5 more years more than 2 times as old as Justin"
3x+3 = 2(x+3) + 5

this solves easily to
3x+3 = 2x + 6 + 5
x = 8, and then 3x = 24


Justin is now 8
Mack is now 24

check:
in 3 years ...
Justin is 11
Mack is 27

is 27 five more than twice 11 ??
2(11) + 5 = 27
YEAHH!

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