Each week, you drive 150 miles. your car gets 25 miles to the gallon, and gas prices are $3 per gallon. how much gas money will you spend on gas each week?

           (150 miles/week) x (1 gallon / 25 miles) x (3 $/gallon)

       =    (150 x 1 x 3) / (25)   (miles-gallon-$ / week-miles-gallon)

       =                      18            $/week .

So if the car gets 25 miles a gallon and you travel 150 miles a week all you would have to do is divide 150 by 25 and the multiply that number by 3 which is $18