Answer:
118.3098592 miles on 20 dollars
Step-by-step explanation:
First determine how many gallons you can get for 20 dollars
20/ 3.55 per gallon = 5.633802817 gallons
We can get 21 miles per gallon
Take the number of gallons times 21 miles per gallon
5.633802817 gallons * 21 = 118.3098592 miles