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This problem says in 2008, the price of gallon of unleaded gas was $4 .2.
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And in 1990, it was only $1 .37 per gallon.
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What is the increase expressed as a percent change? and to be able to figure that out, we need to use the percent change formula, which is our final amount, whatever it is, minus the initial, divided by the initial, and the absolute value of that result multiplied by 100.
00:28
Because before we multiply by 100, we would have our change, but in decimal form.
00:33
And we went in percent change form.
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So our final was what we had in 2008, which was $4 .2.
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Our initial was the price of 1990, which was $1 .37.
00:43
So we'll subtract that and then divide by the initial, which is $1 .37 or $1 .37 again...