A continuous cable of total length l is wrapped around the small pulleys at A, B, C,

Question:

A continuous cable of total length l is wrapped around the small pulleys at A, B, C, and D. If each spring is stretched a distance b, determine the mass M of each block. Neglect the weight of the pulleys and cords. The springs are unstretched when d = l/2.
Given:
l = 4 m
k = 500 N/m
b = 300 mm
g = 9.81m/s2

A continuous cable of total length l is wrapped around