i need you help guys in this A rigid massless disk is freely

i need you help guys in this

A rigid massless disk is freely pivoted about its center. A massless string is wounded around the disk periphery, hangs down the left side and attached to m_B = 0.75 kg. A massless rod, fixed to the disk extended out to 1 kg mass at A. The system is released from rest with theta = 30. What is mass B velocity when theta = 45

velocity = 33.75m/s