Answer: £22.40
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Step-by-step explanation:
The sale price of the shorts is £18
Let's say x is the original price of the shorts.
If there's a 10% discount, then you pay the remaining 90%
sale price = 90% of x = 0.90x
Set this equal to the 18 pounds and solve for x.
0.90x = 18
x = 18/0.90
x = 20
The shorts originally were £20.
The discount saves you 2 pounds.
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Let y be the original price of the jeans before the discount.
The price ratio of jeans to shorts is 7:5. This is before the discount for both items.
So,
(jeans price)/(shorts price) = 7/5
y/20 = 7/5
5y = 20*7
5y = 140
y = 140/5
y = 28
The jeans were originally £28 before the discount.
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Now apply the 20% price reduction for the jeans.
20% of 28 = 0.20*28 = 5.60
You save £5.60 and the sale price of the jeans is 28-5.60 = 22.40 pounds.
Or you can use this shortcut
80% of 28 = 0.80*28 = 22.40
This shortcut works because if you save 20%, then you pay the remaining 80%