A crate with a weight of 57 N rests on a frictionless ramp inclined at an angle of 30 degrees to the horizontal. What force must be applies at an angle of 20 degrees to the ramp so that the crate remains at rest?

I've drew the diagram and I don't know what to do after this:

I know the formula to use is "u (dot) v = |u||v|cosx"

The answer to this problem is 28.5 N and 30.3 N.

Can you please show me a step by step solution to get the answer?