I need some help with my physics homework, elastic collisions in which case both parties are moving, I can do with when one is stationary, but I could use some advice on double motions equations.

A charging bull elephant with a mass of 5230 kg come directly toward you with a speed of 4.45 m/s. You toss a .150 kg rubber ball at the elephant with a speed of 7.91 m/s.
A) When the ball bounces back toward you, what if the speed?
B) How do you account for the fact that the balls kinetic energy has increased?

I don't quite understand why you would throw a rubber ball to stop an elephant, but whatever the questions still matter
any help out there?