How would i solve these two problems?

Physics 1351 - Discussion 6 Held Block A 4.0 kg block is held at rest against a vertical wall by a horizontal force of 150 N. a) What is the magnitude of the frictional force exerted by the wall on the block? (Hint: make sure to draw a free-body diagram of the block. Friction may be in an unusual direction in this problem!) ush normal b) What is the magnitude of the minimum horizontal force needed to prevent the block from falling if the coefficient of friction between the wall and the block is us = 0.40