SOLUTION: Question: Jake is 13 years old. In 3 years his grandpa will be twice as old as Jake's dad, and in 7 years his grandpa will be four times older than Jake. How old is Jake's dad? I'

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Question 1002578: Question: Jake is 13 years old. In 3 years his grandpa will be twice as old as Jake's dad, and in 7 years his grandpa will be four times older than Jake. How old is Jake's dad?
I've tried 13*4=52. 52-7=45. 45+3=48. 48/2=24.
I'm not sure what steps I'm missing or what math I'm doing wrong

Found 2 solutions by josgarithmetic, mananth:
Answer by josgarithmetic(39620) About Me  (Show Source):
You can put this solution on YOUR website!
j, g, d, for Jake, Grandpa, Dad


Examining the description very carefully, you should be able to form this system of equations:
system%28j=13%2Cg%2B3=2%28d%2B3%29%2Cg%2B7=4%28j%2B7%29%29

One of the variables is already given as known, so you can substitute for it now and you will have a system of two equations, just in the unknown variables, g and d.

system%28g%2B3=2d%2B6%2Cg%2B7=4j%2B28%29

system%28g=2d%2B3%2Cg=4j%2B21%29

system%28g=2d%2B3%2Cg=4%2A13%2B21%29

system%282d=g-3%2Cg=52%2B21%29

highlight%28g=73%29---------Grandpa;
but still you want to know d, from the other equation in the last system;

2d=g-3
2d=73-3
d=70%2F2
highlight%28highlight%28d=35%29%29-----------Jake's dad.

Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!

Jack is 13 now
After 7 years he will be 20
grandpa will be 4 time older than Jake
20 + 80 = 100
(three years from now means 4 years earlier )
4 years ago grandpa was 96
and at that time he was twice dad,s age
dad,s age = 48
dads age now is 48-3 = 45 years