Answer:
If the phone is on sale for 30% off, this means the phone has had 30% of its original price taken off to arrive at the new price of £128. To find the original price of the phone, we can use the equation:
Original price = Sale price / (1 - Discount percentage)
In this case:
Original price = 128 / (1 - 0.30)
When we calculate this we get:
Original price = 128 / 0.7
Original price = £183.33
So the phone cost £183.33 before the sale.