Answer:
At the beginning, the box has 12 ounces of cereal.
Sue eats 1/6 of the box which is 12*(1/6) = 2 ounces.
Glen eats 2/3 of the box which is 12*(2/3) = 8 ounces.
So, the total ounces that they have eaten is 2+8 = 10 ounces.
Therefore, 12-10 = 2 ounces are left in the box.