Answer:
70%
What is given: 20% of one color, and 10% of another.
That gives us 30% of 100%.
Take away the smaller percentage from the limit, which would be 30 from 100.
You are left with 70%, which means that 20% is red, 10% is blue, and 70% is green.
I hope i helped! (If its not correct I will edit my answer before i submit the test :D