Answer:
1:2
Explanation:
First, find how many are green
Add up the number of blue and red ones:
10 + 15 = 25
Subtract this from 50
50 - 25 = 25
So, 25 are green.
Since there are 50 marbles in total, the ratio will be 25:50
This can be simplified, since both numbers are divisible by 25.
So, the ratio is 1:2