How do you find an original price after a percentage increase?

The new price is (100 + increase)% of the original. Divide the new price by that multiplier. For 20% up, divide by 1.2.

Why is subtracting 20% from the sale price wrong?

The 20% was 20% of the original, not of the sale price. Subtracting 20% of the new number uses the wrong base.

Are reverse percentages on Foundation?

Yes. Both tiers meet them. Higher wraps them in longer contexts and successive changes.

Reverse percentages GCSE Maths questions

Reverse percentages GCSE Maths questionsReverse percentages GCSE Maths questions: find the original after an increase or decrease. Divide by the multiplier that was applied. Marked practice.Start free GCSE Maths test · Pricing