How do you split 40 pencils five ways

Can someone me with my hwplz(only the circled ones)

For each proportion find the unknown number x 1/5/8=×/15

The number if marbles of different colors stored in a hat is listed below: 4 red marbles 10 green marbles 7 blue marbles. without looking in the hat, dan takes out a marble at random. he replaces the marble and then takes out another marble from the hat. what is the probability that dan takes out a blue marble in both draws?