# Age now and then

Discussion in 'Personal Homework Help' started by Drew, Apr 28, 2017.

1. ### DrewNew Member

I brute forced this and got a wrong answer, logic tells me is right. I tried the calculator here but maybe messed up the equation using another users problem as an example. Having no luck.

Problem:
Jacob is 4 times the age of Clinton. 8 years ago Jacob was 9 times the age of Clinton. How old are they now and how old were they 8 years ago?

Let j be Jacob's age and c be Clinton's age. We have:
1. j = 4c
2. j - 8 = 9(4c - 8)
Substitute (1) into (2)
(4c) - 8 = 36c - 72

Using our equation solver, we get c = 2
Which means j = 4(2) = 8

8 years ago, Jacob was just born. Which means Clinton wasn't even born yet.

3. ### DrewNew Member

Thank you, but I'm going to have to talk to my teacher about how someone can't be 9 times older than nothing....

Yes, it was a bit odd. I'll do more research if she comes back on that one. I may have read it wrong. Let me know.

5. ### DrewNew Member

she wrote it down wrong! The 9 should have been a 10.

So I tried 4c-8=40c-80 in the equation solver and it also came back with C=2 which was the same answer you got before?

6. ### DrewNew Member

she wrote it down wrong! The 9 should have been a 10.

So I tried 4c-8=40c-80 in the equation solver and it also came back with C=2 which was the same answer you got before?
oh and my brute force answer was 12-48 and 8 years earlier was 4-40

I read it wrong before. Here you go:

Jacob is 4 times the age of Clinton. 8 years ago Jacob was 10 times the age of Clinton. How old are they now and how old were they 8 years ago?
1. j = 4c
2. j - 8 = 10(c - 8)
Substitute (1) into (2)
(4c) - 8 = 10c - 80

Equation solver gives us c = 12 which means j = 4(12) = 48.
8 years ago, j = 40 and c = 4 which holds the 10x rule.

8. ### DrewNew Member

Thank you, I see what I did wrong!