In Figure 5 the 80 kg block rests on a rough 25° incline and is tied by a light rope, parallel to the incline and passing over a smooth pulley, to a hanging mass m. Using the friction coefficients on the figure, determine (a) the largest mass m for which the block stays at rest (in kg), (b) the smallest mass m for which the block stays at rest (in kg) and (c) the acceleration of the block when m = 60 kg (in m/s²).