melody bought a DVD priced 17.50 cost 18.81 after tax. What was the percent in sales tax?
When you purchase something, you pay 100% of it--all of it. When you have a sales tax, let's say 10 percent, you're paying 110% (100+10). In other words, you're paying 1.10 times more than your original amount. In this case, you don't know how many times more Melody is paying. 17.5 times a number=18.81 ---> 17.75 x N=18.81 Solve for N.
N=1.075 .This means she is paying 1.075 times more than she usually does. Convert 1.075 into a percent by multiplying by a 100. She is paying 107.5 %, which means she is paying 7.5% more.