33)
first consider the free body diagrams
now for the mass M,
from fbd, T = Mg - Ma
For the combined mass (m+M')
T = (M'+m)a
equating both Mg =(M' + M + m)a
so a = Mg / (M' + M + m)
now consider the fbd of the mass m ,
ma cos x = mg sin x
so a = g tan x
Now equating this a with the formerly obtained a,
Mg/(m+M+M') = g tan x
so M cot x = M + M' +m
M = (M'+m/ cot x - 1)
ans