To do this first we will divide the amount of dollars (20) by the amount of dollars 1 gallon is for (4). Then we will multiply the amount of times 4 goes into 20 by 32 and the answer will be the amount of miles she can drive worth $20.
20 ÷ 4 = 3
3 × 32 = 96
So, Margie can drive 96 miles in $20.
Hope I helped ya!! xD