# Reverse Percentages Finding the original price after deduction or increase Let’s do the first one together: A radio sells for £63, after a 40% increase.

## Presentation on theme: "Reverse Percentages Finding the original price after deduction or increase Let’s do the first one together: A radio sells for £63, after a 40% increase."— Presentation transcript:

Reverse Percentages Finding the original price after deduction or increase Let’s do the first one together: A radio sells for £63, after a 40% increase in the cost price. Find the cost price.

Reverse Percentages A radio sells for £63, after a 40% increase in the cost price. Find the cost price. The selling price is 100% + 40%, so £63 = 140%. Calculate 1% 140% = £63 1% = £63/140 1% = £0.45 The cost price is 100%, so multiply £0.45 by 100 Cost price = 0.45 x 100 = £45

Another example A packet of washing powder is advertised as having '20% extra powder'. If it contains 1.32kg. What would the original pack contain? 1.02kg? 1.1kg? 1.06kg? 1kg?

Another example A new car falls in value by 30% in a year. After a year, it is worth £8,400. Find the price of the car when it was new. Remember that the original price of the car is 100%. Original price = 100%. Second-hand price = 100% - 30% = 70%. So £8,400 = 70% of the original price. So 1% of original price = £8,400 ÷ 70 Original price = 100% = 100 x 1% = 100 x (£8,400 ÷ 70) = £12,000.

Footballers £ listing The Association of Football has decided to re-price some of their footballers depending on their previous performance. Here are some of the new prices and their percentage increase or decrease: Ronaldo 113.4m INCREASE 40% Messi 160m DECREASE 20% Di Maria 71.88m INCREASE 19.8% Van Persie 18.75m DECREASE 25% Neymar 57.5m INCREASE 9.8% Falcao 40m INCREASE 5% Can you work out any 3-6 players’ original prices before the re-pricing?

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