Ican't seem to figure this question out. i've worked it out but i keep getting stuck

If f(x)=x^3 and g(x)=2x+7 when g(x)=-5

On average, how many more hits will he get when he bats 100 times at home during the day as opposed to 100 times away at night?

Aball is dropped from a height of 10m above the ground. it bounce to 90% of its previous height on each bounce. what is the approximate height that the ball bounce to the fourth bounce?