I don't know how to do question c at the very bottom. Could somone please explain. Thank you!

170-68 = 102 meters to catch the antelope
from a) 1 stride = 7 meters in 0.28 seconds
102/7 = 14.57 strides x 0.28 = 4.08 seconds total
V=D/T = 102/4.08 = 25 meters/second
1m/s = 3.6 K/H
25 x 3.6 = 90 Kilometers/ hour