Apaper bag has 3 red and 7 blue marbles. if the first marble is red what is the probability of getting a blue marble on the second draw ?

7/9

Step-by-step explanation:

you have 2 red left and there is 9 total which means that 7 of these 9 are blue.

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: