Agallon of gasoline cost 30 cents in 1960 and $1.30 in 1980. what was the percent increase in the price of gasoline

A gallon of gasoline cost 30 cents in 1960 an 
$1.30 in 1980
percent increase in the price = ?
first we have to convert cents into dollars so that both amounts have to be in same unit
30 cents = $0.3
increase in gasoline cost = $1.30 - 0.3 = $1
now for calculating percent increase divide this with the new amount and than multiply with 100
percent increase = ($1 / $1.30) x 100 = 76.92% = 77% approx.
so, there is 77% increase in the price of gasoline

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