A and B are partners in a firm sharing profits in the ratio of 5:3. They admit C as a new partner for 1/7th share in the profits. The new profit sharing ratio will be 4:2:1. The sacrificing ratio of A and B is:

3:5

The correct answer is option 3- 3:5.

Old ratio = 5:3 (A & B)
New ratio = 4:2:1 (A, B & C)

Sacrificed share = Old share - New share

Sacrifice of A = 5/8 - 4/7
                    = (35-32)/56
                    = 3/56

Sacrifice of B = 3/8 - 2/7
                    = (21- 16)/56
                    = 5/56

Sacrificing ratio = 3/56 :5/56
                        = 3:5