average rate of change

Question

f(x)=2/t; x=a, x=a+h

Answer 1

You have two variables and that does not help.  I think you mean :

f(t) = 2/t or f(x) = 2/x

so f(a) = 2/a

f(a + h) = 2/(a + h)

Answer 2

Students,on average,read 2books per week.there are about 125 fiction books on the back bookshelves. The fiction novels on the shelves have an average of 20 chapters each. How long would it take for an average student to read all of the fiction books on our back bookshelves?