a rectangle has a perimeter of 22 centimeters. the length of the shortest side is 3 centimeters. what is the length of the longest side? a)      7 cm b)      5 cm c)      6 cm d)      8 cm    

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: