Question

In a sale, the prices in a shop were all decreased by 20%. After the sale, they were all increased by 25%. What was the overall effect on the shop prices? Explain how you know.

Answer 1

Prices changed from 100% price to 80% price due to sale.
 
100% - 20% = 80%

THEN increased by 25% so 

80% + 25% = 105%

so the overall effect is that the price rose from the original (100%) to 105%
so a 5% increase