Please help, it's really tough!! :(

Physics:

(Take g = 10 m/s2 in this question.) The ends of a light inextensible string, of length 0.7 m, are attached to two fixed points A and B at the same horizontal level, where AQ = 0.4 m and QB = 0.1 m. A particle of mass 0.2 kg is attached to the string at the point P, where AP = PB = 0.3 m. The particle hangs in equilibrium, with the string passing over a small smooth peg fixed at the point Q in the horizontal line between A and B at a distance of 0.1 m from B, as shown below. Give three reasons why the tensions in the three parts, AP, PQ, and QB, of the string have the same value, and find this value. Also, determine the angle between QA and the force exerted on the string by the peg. Refer figure below:

http://s919.photobucket.com/albums/ad39/eqreal87/?action=view&current=DSC01488.jpg