Please help i really need to get this done

Given f(x) = 17-x^2what is the average rate of change in f(x) over the interval [1, 5]?

The late fee for library books is $2.00 plus 15¢ each day for a book that is late. if maria’s fee for a late book was $3.20, write and solve a linear equation to find how many days late the book was.

Question: what is the value of x 4x-2= (-7) +5x. it would be greatly appreciated if someone could actually explain to me step by step