Engineering mechanics question about weight/cables/pulleys

[bobmarly12345]

Homework Statement

An assembly shown in the picture, GH , HK, HNL are three cables. the mass of box L IS 64Kg,
a) determine the mass of box K in order to make angle theta as 25 degrees
b) determine the reaction forces at supports G and N
c) calculate required cable diameter when tensile strength of the cable is 20MPaI can't seem to do these questions and its stressing me out because i could do it before but I've totally forgotten how to now. any help would be more than great!

Homework Equations

The Attempt at a Solution

 

[pongo38]

First identify which principles will be involved. In this case, static equilibrium. What do you know about equilibrium that might apply in this case? What other principles might be involved?