Which set of ordered pairs represents y as a function of x? A: {(2,5), (3,1), (2,1), (4,7)}
B: {(3,2), (4,3), (5,2), (2,6)}
C: {(1,3), (3,5), (2,5), (1,6)}
D: {(4,7), (4,6), (4,4), (4,1)}

May I get an explanation? I'm tired of looking through the internet and not finding anything :(

The radius of the earth is two times the radius of the moon. what fraction of the volume of the earth is the volume of the moon?

Right triangle xyz has a right angle at vertex y and a hypotenuse that measures 24 cm. angle zxy measures 70º. what is the length of line segment xy? round to the nearest tenth. 8.2 cm 8.7 cm 22.6 m 25.5 cm

Abag contains 3 red marbles, 2 blue marbles, and 2 green marbles. one marble is picked, then another marble. assume that the selections are made with replacement. a) find the probability of picking two red marbles with replacement. b) find the probability of picking a red marble and a blue marble. assume the selections are made without replacement. c) find the probability of picking two red marbles without replacement. d) find the probability of picking a red marble and a blue marble without replacement.