Resolve all forces into components in the direction of Q and normal to Q

(with lets say positive upwards). Then as the body is in equilibrium the

sum of each components is zero. so

Put phi = theta-10 degrees

p_1 =P(parrallel toQ) = -10 cos(10)

p_2 =P(orthog toQ) = -10 sin(10)

r_1 =R(parrallel toQ) = -R cos(phi)

r_2 =R(orthog toQ) = R sin(phi)

then:

p_1 + r_1 = Q = -20

p_2 + r_2 = 0.

Which is a pair of simultaneous non-linear equationswhich you will have to

solve for phi and R.

RonL