Four years ago Sumon's age was half of what it will be in eight years. How old is Sumon?
A
8
B
12
C
16
D
none of these
Correct Answer: 16
Let Sumon's age be S. Four years ago, his age was (S - 4). After eight years, his age will be (S + 8). Then, S - 4 = (S + 8)/2 or, 2(S - 4) = S + 8 or, 2S - 8 = S + 8 or, 2S - S = 8 + 8 or, S = 16 years.