Can someone help me with this please

Find the average rate of change for f(x) = x2 − 3x − 10 from x = −5 to x = 10.

Subscriptions to a popular fashion magazine have gone down by a consistent percentage each year and can be modeled by the function y = 42,000(0.96)t. what does the value 42,000 represent in the function?

It says factor each expression completely 8y+48