Answer:
If the portion of frozen casserole occupies 1/3 of the pan, it can be affirmed that it occupies 0.333 of it. Thus, if someone eats 1/4 of the pan, it could be stated that they are eating 0.25 of it.
Therefore, to determine the fraction of the portion that has been eaten, the following calculation must be performed:
33 = 100
25 = X
(25 x 100) / 33 = X
2500/33 = X
75.75 = X
25/33 = X
Therefore, the fraction of the serving that was eaten is 25/33, or 76% of the serving.