In eight years, Jack will be 2/3 as old as Tom. Four years ago he was 1/3 as old as Tom. Let the age of Jack be J and that of Tom be T.

According to the data provided

J + 8 = (2/3)*(T + 8) and J - 4 = (1/3)*(T - 4)

=> 3J + 24 = 2T + 16 and 3J - 12 = T - 4

Subtracting the two equations gives

T + 20 = 36

=> T = 16

and J = 8

**Presently Jack is 8 and Tom is 16.**