Reverse Percentages Explained: Finding the Original Value

If a jumper costs £80 after a 20% discount, why is the original price not £100 simply because we add 20% back? The key is to identify which percentage of the starting price the final amount represents. This lesson introduces reverse percentages, where the final value and the percentage change are known but the original value is unknown. The central question is how to work backwards from the changed value to the original amount.