Replacing the given values in formula (a) we have:
Amount Saved = Original Price x Discount in Percent / 100. So,
Amount Saved = 1/5 x 90 / 100
Amount Saved = 18 / 100
Amount Saved = £0.18 (answer).
In other words, a 90% discount for an item with an original price of £1/5 is equal to £0.18 (Amount Saved).
Note that to find the amount saved, just multiply it by the percentage and divide by 100.