The batteries cost 3.50. We want to find out how much they cost after a 6 percent sales tax.
First take the percentage and change it into decimal form, then multiply with the original number like I've done below.
3.50 * 0.06 = 0.21
3.50 + 0.21 = 3.71
Then you simply add the amount to the original 3.50 to get $3.71 as your price after sales tax.
