Signs in a department store read, "75% off original prices when you take an extra extra 50% off already reduced prices." By what percent were original prices reduced before today's sale?
Here's my common sense, but unconventional, way of solving this problem.
If the original price was $10, then 75% off would mean it now sells for $2.50.
2.50 is 50% of $5.00. The original discount must have been 50%.
Perhaps a math tutor will show you a more mathematical way of solving this problem.