(192 mi)/(32 mi/gal) = 6 gal
6 gallons of gas are required.
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Note that the units on the numbers give a clue as to how to do the calculation. You want gallons in the numerator of the result, so must divide by (miles/gallons), which has gallons in the denominator. If you divide miles by those units, the miles cancel and the result is gallons, as you want.
