Madelyn hopped 12 times in 15 seconds. how many hops can she do per minute?

There four sets of 15 in a minute so you would multiply 12x4 so she would be able to hop 48 times in a minute.

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so: