Physics Work,Power & Energy Level: Misc Level

The lead female character in the movie Diamonds Are Forever is standing at the edge of an offshore oil rig. As she fires a gun, she is driven back over the edge and into the sea. Suppose the mass of a bullet is 0.009 kg, and its velocity is +712 m/s. Her mass (including the gun) is 45 kg.

a) What recoil velocity does she acquire in response to a single shot from a stationary position, assuming that no external force keeps her in place?

b) Under the same assumption,what would be her recoil velocity if, instead, she shoots a blank cartridge that ejects a mass of 5.0x 10-4 kg at a velocity of +712 m/s?