Set up a Proportion for:
You pay $3.69 for a gallon of gasoline. This is 90% of the price of a gallon of gasoline one year ago. What was the price of a gallon of gasoline one year ago?
\(\$3.69=\dfrac{x\cdot 90}{100}\\ x=\dfrac{\$3.69\cdot 100}{90}=\$4.10\)
The price of a gallon of gasoline one year ago was $4.10.
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