Please solve

The resale value R (in dollars) of a particular type of laser cutting tool t years after its initial purchase is approximated by R(t) - 700,000e -0.28t a. What is the decay rate of the resale value? Note: The decay rate will be negative. b. Find the rate at which the resale value is changing 10 years after the initial purchase. R' (10) = c. Find the rate at which the resale value is changing 15 years after the initial purchase. R' (15) =