At best buy they have a stereo system that sells for $2,200 and it's on sale for 15% and sales tax is 7% what is the final cost

The sales price is 85% of the original $2,200, which can be calculated as follows: .85(2,200) = 1870 Assuming you meant 15% discount price..

Now we need to find a 7% sales tax, which can be calculated as follows:

.07(1870) = 130.90

Now we add the sale price and the sales tax: 1870 + 130,90 = $2000.90 for the total cost.