Zeus industries bought a computer for $2280. it is expected to depreciate at a rate of 30% per year. what will the value of the computer be in 3 years?

There is a formula for this but I can't quite remember what it is. This is another way to find the

First, you have to find what 30% of the original value is. 
To find the value, the trick I use is:
= 
You need to know what is 30% of $2280.
You are looking for "is" so in the equation, we can set "is" to x. 
The percentage is 30%
And you are trying to find 30% Of $2280 so 2280 is your "of" value.
(Hope that wasn't too confusing)

But now your equation is

When you cross multiply, you get
100x = 2280 * 30

solve for x
100 x = 68400
x = 684
which means that after the first year, the value will depreciate or go down by $684

After one year, the value of the computer is
$2280 - $684 = $1596

Doing the same thing again, this time finding 30% of 1596 = $478.8, you find that after two years, the value is 
$1596 - $478.8 = $1117.2

Once again, for the third year, 30% of $1117.2 = $335.16
$1117.2 - $335.16 = $782.04
$782.04 is your final answer

*sorry I couldn't remember the formula but hope this helped at least :)

Number nine is f(x)= 40x : ) hoped i ya