Conservation Of Momentum In An Explosion

A 0.50 kg firecracker, initially at rest, explodes into three fragments. Two fragments, each with a mass of 0.10 kg, travel at speeds of 30 m/s and 40 m/s along perpendicular paths. What is the velocity of the third fragment, which has a mass of 0.30 kg? The direction should be measured as an angle relative to the velocity vector of the 30 m/s fragment.