You'd want an expression which relates to x, y and d. The distance d is x times pi times 100. One divides back by pi and by y to get the # of revolutions (that 100 :)) ) and so one gets y 100 x as the number of revolutions.
The number of revolutions the second wheel makes in covering distance d is given by y 100 x , where x is the diameter of the first wheel and y is the diameter of the second wheel. This relationship comes from comparing the circumferences and the distances covered by both wheels. We derived this formula by equating the distances traveled by both wheels based on their diameters and the number of revolutions made.
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