Mr. Stevens is 63 years older than his grandson, Tom. In 3 years Mr. Stevens will be four times as old as Tom. How old is Tom?

set x = age of Mr Stevens, y = age of his grandson.

 

we have a set of equation:

 

x - y = 63

(x+3) = 4(y+3)

 

solve it and we have x = 81, y = 18.