Question

15 years from now rail age will be 4times his present age. What is his present age

Answer 1

5 may be the present age of him.
5+15 =20
20=5*4

Answer 2

X + 15 = 4 *X
15 = 4X - X
15 = 3X
15/3 =X
5 = X
Or X = 5