Question

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 Percent Proportion Show your work

Answer 1

Price of gallon of gasoline one year ago is $ 4.1

Solution:

Given that you pay $ 3.69 for a gallon of gasoline

This is 90% of the price of a gallon of gasoline one year ago

To find: price of a gallon of gasoline one year ago

We can solve this sum by setting up proportion

Let "x" be the price of gallon of gasoline once year ago

By proportions we get,

`(3.69)/(x) = 90 \%`

`(3.69)/(x) = (90)/(100)`

`3.69 * 100 = x * 90\\\\369 = 90x\\\\x = (369)/(90)\\\\x = 4.1`

Thus price of gallon of gasoline one year ago is $ 4.1

Method 2:

you pay $ 3.69 for a gallon of gasoline

Let "x" be the price of gallon of gasoline once year ago

3.69 = 90% of the price of a gallon of gasoline one year ago

3.69 = 90 % of x

`3.69 = (90)/(100) * x\\\\369 = 90x\\\\x = 4.1`

Thus price of gallon of gasoline one year ago is $ 4.1