This is an exponential growth/decay problem, and it doesn't really matter which when it comes to the equation because they are both pretty much the same. The formula is A = Pe^(rt), where A is what you end up with, P is the principle value of the object, e is euler's number, r is the rate of decay or growth, and t is the time in years. Since we are looking at depreciation or decay, our r value will be negative. A is what we are solving for (the ending value), P is 2857, r is -.24 and t is 3. So our formula, set up properly, looks like this: A = 2857e^(-.24*3). The first thing to do is to simplify the exponents by multiplying them: A = 2857e^(-.72). Now we're ready to solve! On your calculator, you have a 2nd button and a LN button, when you hit 2nd-->LN you'll get e^( . Enter in the -.72 and then hit enter. You should get .4867522. Now multiply that by 2857 and you'll get 1390.65. That's what the computer will be worth in 3 years if it depreciates at that rate.
