Today Jim is twice as old as Fred and Sam is 2 years younger than Fred. Four years ago Jim was 4 times as Sam. How old is Jim now?

let J, S, and F = the current age of Jim, Fred, and Sam, respectively and create the equations:

J = 2F

And

S = F - 2

S + 2 = F

And

J - 4 = 4(S - 4)

J - 4 = 4S - 16

J = 4S - 12

Since J = 2F we have:

2F = 4S - 12

F = 2S - 6

Since S + 2 = F, we have:

S + 2 = 2S - 6

8 = S, so J = 4 x 8 - 12 = 20.

Answer: 20