If 2 hours of TV had 40 commercials, how many commercials were in 1/2 hour?

10

Since there are 40 commercials in 2 hours you divide 40 by 2 to find out how many commercials there were in one hour. Then divide by two again bc 1/2 hour is 30 minutes and you get 10.

3/6   and 9/18

step-by-step explanation:

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: