a class voted for either rollerblading, swimming, or biking as their favorite summer activity. if rollerblading got 21% percent ad swimming got 40%, what percentage of the class voted for biking?

 39% voted for biking

Step-by-step explanation:

Add the other two percentages and subtract from 100

40 + 21 = 61

100 - 61 = 39

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:

20%

step-by-step explanation: