Answer:
P = 0.8
Step-by-step explanation:
The probability is the division between the number of marbles that are red or green over the total number of marbles in the bag.
So, there are 15 marbles in the bag:
8 red + 3 blue + 4 green = 15 marbles
And 12 of them are red or green:
8 red + 4 green = 12 marbles
Therefore, the probability is equal to: