$A$ is three times as old as $B$. $C$ was twice-as old as $A$ four years ago. In four years' time, $A$ will be $31$. What are the present ages of $B$ and $C$?

Let the present ages of A, B, and C be A, B, and C. Since A + 4 = 31, A is currently 27. Because A is three times as old as B, B is 27 / 3 = 9. Four years ago, A was 23, and since C was twice as old as A at that time, C was 46. Adding four years back to C's past age gives C's present age as 50.

• Thanks
• Wrong explanation