Find the average content of oxygen in the pond over the

Question

Question: WASTE DISPOSAL When organic waste is dumped into a pond, the oxidization process that takes place reduces the pond's oxygen content. However, in time, nature will restore the oxygen content to its natural level. Suppose that the oxygen content t days after organic waste has been dumped into a pond is given by

f(t) = 100((t² + 10t + 100)/(t² + 20t + 100))

Percent of its normal level. Find the average content of oxygen in the pond over the first 10 days after organic waste has been dumped into it. Hint: Show that

(t² + 10t + 100)/(t² + 20t + 100) = 1 - (10/(t + 10)) + (100/(t + 10)²)