SOLUTION: Last month the price of wheat was $20 per kg. The price now is $25 a kg. By what percent should a family reduce its consumption so as to keep their expenditure fixed?

Question 931734: Last month the price of wheat was $20 per kg. The price now is $25 a kg. By what percent should a family reduce its consumption so as to keep their expenditure fixed?
Answer by TimothyLamb(4379) (Show Source): You can put this solution on YOUR website!
x = kg of wheat consumption at $20/kg
y = kg of wheat consumption at $25/kg
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fixed wheat expenditure:
20x = 25y
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y/x as ratio:
20x = 25y
y/x = 20/25
y/x = 5*4/5*5
y/x = 4/5
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y/x as percent:
y/x = 4/5 * 100
y/x = 80%
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reduction in consumption as ratio:
y/x = 4/5
y = 4/5x
(x - y)/x
(x - 4/5x)/x
(5/5x - 4/5x)/x
1/5
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reduction in consumption as percent:
1/5 * 100 = 20%
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