a/b The decay can be modeled by this equation, (1 - r), the r being the rate of decay. So it would be 1-0.115. (0.115 is your answer for a) You have to convert the percent into a decimal by moving the deicmal place two places to the left. 0.885 is your answer for b.
c. For function notation, that just means write an equation. So you want your decay times your inital. V(t)=15000(0.885)^x. We get the V(t) from the directions that they want us to put it in; it's basically y.
d. Since it's two years, plug in 2 for x. This shows the decay after two years
V(t)=15000(0.885)^2
e. As with d, plug in 10 for x. V(t)=15000(0.885)^t
