Answer:
8 rotation will the tires made after frank rides 50 ft.
Explanation:
Given: The tire on franks bike moves 75 inches in one rotation.
If bike of tire move 75 in then rotation of wheel is 1
In 75 in of tire move = 1 rotation 
In 1 in of tire move = 
 rotation 
Now we change 50 ft into inches 
 1 ft = 12 inches 
50 ft = 12 x 50 = 600 inches 
In 1 inch of tire move = 
 rotation 
In 600 inch of tire move = 
 rotation 
Hence, 8 rotation will the tires made after frank rides 50 ft.