Hello!
The equation for an exponential deprecation model like this is
, where a is the starting value, x is the number of years passed, and r is the amount the value deprecates each year.
We know what a and r are: a = 1600, as that is the original cost of the computer, and r = .18, as that's how much it decreases by. Substitute these two into the equation.
We get
. Now, subtract 1 - .18 to get our final answer.
is therefore the final model.
Hope this helps!