The ratio of the present age of A and B is 4 : 3. Ten years ago the ratio was 3 : 2. Find the present age of A.

40 years

                       A      :      B

Present :        4      :      3

10yrs age:     3      :      2

                      ⇓             ⇓

Difference:    1R           1R   =     10 Years

Present ages of A = 4 × 10 = 40 years