a computer is purchased for 800 and each year the resale value decreases by 25% what will be the res

a computer is purchased for 800 and each year the resale value decreases by 25% what will be the resale value after 4 years

Let the resale in year y be R(y). We have:
R(y) = 800 * (1 - 0.25)^y
R(y) = 800 * (0.75)^y

The problem asks for R(4):
R(4) = 800 * (0.75)^4
R(4) = 800 * 0.31640625
R(4) = $253.13