It is important to look at all details given in the question very carefully. Amount of sales tax taken on the sofa = $43.13 Actual cost of the sofa = $575 Let us assume the percentage of sales tax taken = x% Then (x/100) * 575 = 43.13 5.75x = 43.13 x = 43.13/5.75 = 7.50 percent So the percentage of sales tax charged for the sofa was 7.50%.I hope the procedure is clear enough for you to understand. Based on this procedure, similar problems can be done with absolute ease.