We can calculate a percentage change if we are given an original amount and a new amount.
If the price of a train ticket increased from £50 to £60 we can calculate the percentage change using the formula:
Percentage change = change⁄original × 100
The original price is £50 and the new price is £60.
The change (the increase) is £60 − £50 = £10
Percentage change = 10⁄50 × 100 = 20%
The price of a computer is reduced from £350 to £308 in a sale
The original price is £350 and the new price is £308
The change (the decrease) is £42 (350 − 308 = 42)
Percentage change = 42⁄350 × 100 = 12%
We can say that the percentage change is -12% or there is a 12% reduction in the price
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