• From: Sarah Jacobs
  • Date: 14 Feb 1999
  • Subject: Hard Percentage Questions

I can do most percentage increase and decrease questions, but I get some wrong. Like this:

Pat buys a desk in a '15% off' sale for £57.80
What was the original price?

I find 15% of £57.80 and add it back on. I am sure the answer is £66.47 but my teacher says this is wrong.

Please explain why.

Maths Help suggests:

What makes this question slightly harder is that you do not know the original price of the item.

The reduction on the item is 15% of the original price.

But you added on 15% of the reduced price instead. That is why your answer is incorrect.

The important part of solving this problem is to relate the price you were given to the original price:

£57.80 is 85% of the original price.

The correct answer is £68 - have a look at for some guidance about working out percentages.

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