Ok, so work = force x distance. You can either increase force or increase distance to increase your work output. That's the mechanical advantage of a pulley.

So we know the force from the mass is roughly 100 N. If F1= mg and we have 2 tensions pulling up balancing the block, then F2 (pulley force) = 2T. If F2 = F1, which we want it to be, we can say 2T = mg.

If 2T = mg or mg - 2T = 0, then T = mg/2 = F2. Our pulley force is 50 N in this case because we have 2 tensions. This is true in the case that if F2 is pulling straight up, opposing the mass.

However, our force is pulled at an angle(sin is vertical component) so we account that too with F2= mg(sin30)/2 = 25 N. The vertical component must equal to the hanging weight and all of these components add together to give a net force of 0, static equilibrium.

I tried to make it clear lol.