Answer:
4/25
Step-by-step explanation:
Total amount of marbles: 8 + 5 + 12 = 25
With 25 marbles, the probability of picking a red is: 12/25
After 1 red marble is removed, the probability of picking a black is: 8/24 = 1/3
Then, the probability of picking a red then a black marble if you do not replace the first marble is: 12/25 * 1/3 = 4/25