Question

Raul calculated that he would spend $125 on school supplies this year. He actually spent $87.50 on school supplies. What is Raul’s percent of error?

Answer 1

87.5 is 70% of 125 so the percent of error is 30%

Answer 2

Raul spent less than he'd anticipated spending.  To learn how much less, subtract $87.50 from the $125 budget figure.  This "difference" is negative.

Next, divide this "difference" by $125.  The correct result will be a negative decimal fraction.  You must multiply this result by 100% to convert it to a percentage, as required.