A small chemical company that produces an epoxy resin expects its production volume to decline exponentially according to the relationship
yt = 5e-0.25t
where yt, is the production rate at time t. Simultaneously, the unit price is expected to increase linearly over time at the rate
ut = 55(1 + 0.09t)
What is the expression for the present worth of sales revenues from t = 0 to t = 20 at 12% interest compounded continuously?