# Age now and then

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

1. 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. 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. 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. 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. Thank you, I see what I did wrong!