A motor supplies a moment M to the pulley of radius R1. A belt connects this pulley

Question:

A motor supplies a moment M to the pulley of radius R1. A belt connects this pulley to pulley A. Pulleys A and B form a rigid body with a common hub. Ignore the inertias of the three pulleys. Determine the acceleration of the mass m in terms of M, m, R1, R2, and R3.