The free body diagram consists of:
1) Weight force, which is a vertical arrow downward
2) A Normal force that is perpendicular to the ramp.
The Normal force can be decomposed in a vertical component and an horizontal component.
The vertical component, Ny, must equal the weight force, due to equilibrium (rest) condiition =>
Ny = weight = mg = 5.5kg9.8m/s^2 = 53.9 N
By geometry the vertical component of the Normal force, Ny is such that
cos (angle) = N / Ny => N = Ny cos(angle)
=> N = 53.9N cos(angle)
Now use that equation for each option:
a) 0 ° => N = 53.9N cos(0) = 53.9N
b) 12° => N = 53.9 cos(12) = 52.7N
c) 25° => N = 53.9 cos(25) = 48.9N
d) 45° => N = 53.9 cos(45) = 38.1N
