Answer:
1/2 of the jelly beans were either red or green.
Explanation:
Of the 12 jellybeans, 1/3 were red, and 1/6 were green; this means the number of red jellybeans were

and the number of green jellybeans were
.
This means that we have 4+2=6 jellybeans that are either red or green. Now this 6 is

fraction of the total jelly beans.
Therefore 1/2 of the jellybeans were either red or green.
The appropriate number of red and green jellybeans are colored in the figure attached.