Please help!

3. For the following tank reactions, answer the questions below. A 300 L tank is filled with pure water. A copper sulfate solution with a concentration of 15 g/L flows into the tank at a rate of4 L/min. The thoroughly mixed solution is drained from the tank at a rate of4 L/min. a. Write a differential equation (initial value problem) for the mass of the copper sulfate. b. Solve the differential equation