Answer:
50%
Step-by-step explanation:
The total number of marbles is 7 + 3 + 2 + 8 = 20
Blue or red means that the total on any one draw is 7 + 3 = 10
You would expect to draw blue or red 1/2 the time.
Out of 150 throws, you would get 1/2 * 150 which is 75 but that is not what you are asked.
% = (1/2 ) * 100 = 50% of the time