so i wrote that XP = XA + AP and XP = XB - PB
AP = PB so i combined the two equations to ge 2XP = XA + XB
and that 2XR = XA +XC and 2XQ = XB + XC
adding the three equations together, i got 2XA +2XB + 2XC = 2XP + 2 XR + 2XQ and then simplified.
Am I doing it right, or did i miss something