20 total marbles....7 are green
probability on first draw is 7/20...and since the marble was not replaced, the probability on the second draw is 6/19. And since they cant happen at the same time, we multiply
7/20 * 6/19 = 42/380 which reduces to 21/190
M=(y2-y1)/(x2-x1)
(x1,y1)=<span>(−a + 2, b − 3)
</span> (x2,y2)=<span>(a + 2, −b)
then, </span>substituting
m=((-b)-(b − 3))/((a + 2)-(−a + 2))
m=(-2b+3)/(2a)
with
a=/0
