So, basically what they are asking for is the circumference (which is like the perimeter) of the inner and outer circles.
Circumference is: C = 2<span>πr
The radius of the two circles are given so all you need to do is plug it in.
Circumference of the bigger circle (outer tire) is 157ft. Circumference of the smaller circle (inner tire) is 132ft.
The exact answer is 157.07-131.88 = 25.19ft </span>≈ 25ft<span>
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It would be 7:8. Hope that helps.
You multipy 7/8 and 6 and then simplify if needed to get how long it will take