Dimensional analysis is a mathematical method that makes use of the fact that a number or expression with a unit can be multiplied by a factor without changing its value. It is done as follows:
12.8 km/L (25.2 gal) (3.78 L / 1 gal) (1 mi / 1. 61 km)
From the expression above, we cancel units and evaluate it. Then, this gives us,
757.31 miles