how to solve one pulley is 7 cm larger in diameter than a second pulley. the larger pulley turns at 80 rpm, and the smaller pulley turns at 136 rpm. what is the diameter of each pulley

Answer 1

let the diameter of the small pulley be d
let the diameter of the larger pulley be d+7

belt distance covered by smaller pulley in one minute
= 136(πd)
= 136πd
by the larger pulley
= 80(π)(d+7)

so 136πd = 80π(d+7)
divide out the π
136d = 80d + 560
etc

you state the conclusion