Answer:
8
Step-by-step explanation:
Let's say there are 3*x red marbles in the bag. As the ratio of red to blue is 3:2, that means that there are 2*x blue marbles in the bag. The total marbles are then
3*x+2*x= 20
= 5x
Divide both sides by 5 to get
x=4
2*x is the amount of blue marbles, and 2*x = 8
