Consider the following sequence of reactions to produce major product (A)

Molar mass of product (A) is $$gmol^{-1}$$. (Given molar mass in $$gmol^{-1}$$ of C : 12, H : 1, O : 16, Br : 80, N : 14, P : 31)

The sequence of reagents supplied in the question carries out electrophilic bromination on a methyl-substituted benzene ring.
A methyl group is electron-releasing; therefore it directs the incoming electrophile ($$Br^+$$) preferentially to its ortho and para positions. Because of steric hindrance the para product is obtained in the largest amount.

Hence the major product $$\text{(A)}$$ is para-bromotoluene, having the molecular formula $$C_7H_7Br$$.

Molar-mass calculation (using the atomic masses given in the question):
$$\text{Molar mass of }C_7H_7Br = 7(12) + 7(1) + 80 = 84 + 7 + 80 = 171\ \text{g mol}^{-1}$$

Therefore, the molar mass of the major product $$\text{(A)}$$ is

$$\boxed{171}$$