I have an experience. My organization is regulatory financial organization. A team lead who is black came up to me for a question. How to compute change of value in %? For example 56 change 75 what is percentage of change? He knows how to get change 75-56 = 19 but don’t know how to get percentage change. I swear to God. It’s true story. He is a team lead of financial organization! But he is extremely articulate and speaks very well. I’m not English speaker but to me, his talk is excellent.
Actually, a lot of people are confounded with percent problems that they don’t understand.
One of the issues I’ve seen is the question of whether the base for the percent calculation is the old number (usually) or the new number (when you want to confuse someone).
In your problem, 75 is offered for something which costs 56. So the % should be based on the 56. 19 is what % of 56. But that is not what is in question, the question is what % of the 75 is to be returned? 19 is what % of 75. When the cost is 56. To me the issue really is why is the % change important?