What is the ratio of this force to the antelope weight

Compute each part of given problem:

Problem: An impala is an African antelope capable of a remarkable vertical leap. In one recorded leap, a 45 kg impala went into a deep crouch, pushed straight up for 0.21 s, and reached a height of 2.5 m above the ground.

Part A: To achieve this vertical leap, with what force did the impala push down on the ground?

Part B: What is the ratio of this force to the antelope's weight?

I need help to find with what force the impala push down on the ground.