Let's draw the free body diagram of the solid cylinder.
Using the condition of the equilibrium of the cylinder; In the direction of inclined plane, T+f−mgsin60∘=0 In the perpendicular direction of inclined plane,In the perpendicular direction of inclined plane, N−mgcos60∘=0 ⇒N=mgcos60∘ The frictional force between the rough surface and cylinder is f=µsN ⇒f=0.4mgcos60∘⇒f=0.2mg or f=