Acar 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