10 years ago, the age of father was thrice the age of his son. Ten years hence father age will be twice that of his son. The ratio of present age of father and son is
a)	9:2	b)	7:3	c)	5:2	d)	13:4

Let the present age of father be years and that of son be  years.

∴ According to problem, we have

                                                                                    …(i)

And                                                                           …(ii)

Solving (i) and (ii), we get

Required ratio =70:30 or 7:3

Alternative Method:

Let 10 years ago age of father and son were and respectively then

According to problem we have ⇒

∴ Required ratio or 70:30 or 7:3