The formula
If I want to reverse this to have minus profit (depreciates) and minus income do I do ???
You can but you can still use the first formula. It just so happens that
For example if a car worth £14000 depreciates by 4% annually.
P = 14000
R = -4
In the compound interest formula it's usually better to have time as an exponent (time is denoted by t) although n works fine so use whichever is easier
Actually I'm confused by the wording
The company bought a new truck
Each year the value of the truck depreciates by 20%
The value of the new truck can be multiplied by a single number to find its value at the end of 4 years.
I did
and
So I did
/Don't think it's correct :/