see

observe the pulley A

it has three forces acting on it

1) T towards left

2)T downwards

3)force  exerted by clamp = F

now since the net force on the pulley has to be zero as it is massless

therefore F =  opposite of the resultant of forces due to two tensions so that net force becomes zero

so resultant force of two tensions is sqrt(T^2 + T^2) = root(2) * T now it's clear that resultant of two equal perpendicular vectors is at an angle 45 degrees with the horizontal.Hence F will be applied by the clamp at angle of 45 degrees & F will be same as root(2) * T in magnitude and opposite in direction

Do rate me for question 31 if you understood if not then do ask ur doubt