Answer:
56 miles
Step-by-step explanation:
According to the question, lets say the miles at x they charge the same rental
    34 + 0.50x = 20 + 0.75x (Solve equation)
    0.75x - 0.50x = 34 - 20
    0.25x = 14
    x = [tex]\frac{14}{0.25}[/tex]
    x = 56
So at 56 miles, they charge the same rental.