Question

Particles A and B, of masses 0.2 kg and 0.1kg respectively, are joined by a light inextensible string. Particle A is placed on a fixed smooth plane inclined at 10degrees. to the horizontal, and is held at rest by a force of magnitude X newtons which acts in a direction parallel to a line of greatest slope of the plane, and the part PB of the string hangs vertically, as shown in the diagram. Find X