Circumference of the wheel is the outer part of the wheel. We know that the wheel is turning "x" times over 423 feet. What we're trying to find is how many turns occur over 423 feet.
What we got to find is the length of the wheel. Wait! They give it to us; the circumference is the length.
The wheel is traveling that length "x" amount of times for 423 feet. So, we have
7 5/6 × x = 423.
Divide to get x by itself and you get 54. The wheel spun 54 times. Any questions then leave a comment. Good luck!