Alright, Marcus. I hope I'm not too late to help.
Green to yellow is 2:5 and yellow to orange is 3:4. Remember that we always reduce ratios to their lowest terms. Since yellow is both 5 and 3, then it has to be 15. Make sense?
If yellow is 15, then we set 2/5 = x/15, letting x = green. 5x = 30, so x = 6.
Again, with yellow being 15, then we set 3/4 = 15/x, letting x = orange. 3x = 60, so x = 20.
Then, the ratio of green to orange is 6:20 = 3:10.
Hope this helps!