The correct calculation should have been: - Percentage decrease =(28000−26500∕28000)×100% =(1500∕28000)×100% =5.36% So, while the student understands the concept of finding a percentage decrease, they made a calculation mistake, possibly by dividing the wrong way, resulting in an incorrect answer. The correct answer is Students can understand the concept of percentage but are not able to understand the percentage of which quantity is to be found.