Mass of rifle is 6kg, mass of bullet is 0.01kg travelling at 350m/s what is the velocity

Use the conservation of momentum formula: m1v + m2v = m1v + m2v

(6kg) (0m/s) + (0.01kg) (0m/s) = (6kg) v + (0.01kg) (350m/s)

0 = (6kg) v + (0.01kg) (350m/s)

- (6kg) v = (0.01kg) (350m/s)

v = ((0.01kg) (350m/s)) / - 6kg

v = - 0.58 m/s to the other direction