Here's a problem. Not sure if I should just sub in or firstly integrate and then sub in. Please help..

an oil company found that the rate of oil production from an oil well is given by a function of time t, in years:

R(t) = [ 60t/t^2 +9 ] + 35

Approx. how many barrels of oil will be produced in the first 5 years of production?!