Question

A is twice as old as B. 10 years ago A was 4 times as old as B. What is the present age of A and B

Answer 1

Answer

A = 2B (one)

A - 3 = 3(B - 3) = 3B - 9 (two)

3A = 6B (multiply both sides of equation one by three)

2A - 6 = 6B - 18(multiply both sides of equation two by two)

Since both equations now have a 6B, solve for A.

2A - 6 = 3A - 18 (we know 6B = 3A)

2A + 12 = 3A (add 18 to both sides)

12 = A (subtract 2A from both sides)

A = 12, so B = 6 (half of A)

Three years ago, A = 9 and B = 3