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

3:5

The correct answer is option 3- 3:5.

Old ratio = 5:3 (R & S)
B admits with 1/7th share
New ratio = 4:2:1 (R, S & B)

Sacrificed share = Old share - New share

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

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

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