A particle of mass m is initially traveling to the right at 0.900c. It collides and sticks

Question:

A particle of mass m is initially traveling to the right at 0.900c. It collides and sticks to a particle of mass 2minitially moving to the left at 0.750c. Determine
(a) The total mass (in terms of m) of the composite particle,
(b) The amount of kinetic energy lost during the collision, and
(c) The velocity (speed and direction) of the composite particle.