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 ?

A 45, 10

B 10, 50

C 9, 50

D 50, 15

Correct Answer: Option C

Let the age of A = A, B = B and C = C

From given

A = 3B

4 years ago,

C-4 = 2(A-4);

After 4 years

A + 4 = 31;

A = 27;
sub in above B, we get B = 9
C = 2(27 - 4) + 4 = 46 + 4 = 50

Hence B = 9yrs and C = 50yrs.