Here's link to the answer:
cutt.us/tWGpn
X=-3y+6 That is the answer.
A = 1/2 bh
A = 1/2 (21)(8)
A = 1/2 (168)
A = 84
To find the probability of both of these occurring, you will multiply the probability of choosing a blue marble by the probability of choosing a purple marble (with no replacement after the first one).
Probability of choosing a blue marble: 17/120
Probability of choosing a purple marble: 18/119
17/120 x 18/119 = 3/140
You will have a 3/140 chance of both of these occurring.