Answer:
[tex]f(x) = (0.85)^x[/tex]
Step-by-step explanation:
Exponential amount of decay:
The equation for an amount that decays exponentially has the following format:
[tex]A(x) = A(0)(1 - r)^x[/tex]
In which r is the decay rate, as a decimal.
Decrease by 15%
This means that [tex]r = 0.15[/tex]. So
[tex]f(x) = (1 - r)^x = (1 - 0.15)^x = (0.85)^x[/tex]
So
[tex]f(x) = (0.85)^x[/tex]
