Ram is twice as old as Shyam. Ten years ago, Ram was four times as old as Shyam. What is Shyam's present age?

Explanation

Let Shyam's age be S and Ram's age be 2S. Ten years ago, (2S − 10) = 4(S − 10). Therefore, 2S − 10 = 4S − 40, so S = 15 years.