To do this first we will subtract d amount of dollars per ride. den we will divide by d amount per mile. lets do it:-
Subtract:-
10 - 2.05 = 7.95
Divide;-
7.95 ÷ 20 = 0.3975
So, you can drive about 3 miles so your total can be $10 or less.
Hope I helped ya!! xD
