Could you help me to solve me this problem and tell me the formula for the calculation?

An amusement company maintains records for each video game it installs in an arcade. Suppose that C(t) and R(t) represent the total accumulated costs and revenues (in thousands of dollars), respectively, t years after a particular game has been installed and the derivatives C'(t) and R'(t) are the functions below. C'(t)=3 and R'(t)=7 -O.3t Find the area between the graphs of C' and R' over the interval on the t-axis from 0 to the useful life of the game and interpret the results. What is the useful life of the game? t= 2.8 years (Round to the nearest tenth as needed.) The area between the two curves is D square units. (Round to three decimal places as needed. Use the answer from the previous step to nd this answer.)