If you're having trouble - Click each button to enter your quantities. Don't add extra symbols like percent and dollar signs. (This includes euros or any other form of money.) If you're having trouble finding the percentages, look at the problem carefully. Look for anything relating to a percent. For the original price, enter the sub total. That's the sum of all of the prices within your problem, if there's more than one. I hope this helps!
Proportions.