A car uses one gallon of gasoline for every 20 miles. If a gallon of gasoline costs $3.98, how much will the gas cost, to the nearest dollar, to travel 180 miles?

(1 gallon) / (20 miles) = (x gallons) / (180 miles)

1/20 = x/180

1*180 = 20x

180 = 20x

20x = 180

x = 180/20

x = 9

It takes 9 gallons of gas to drive 180 miles

(9 gallons) * (3.98 dollars/1 gallon) = 9*3.98 dollars = 35.82

Round to the nearest dollar: 35.82 - - - > 36

It costs $36 to travel 180 miles