From a set of eight marbles, five red and three white,
you choose one at random. What are the odds in favor
of choosing a red marble
5/8 is the probability of choosing red.
That is probabily what they want.
"Odds" (as stated at a horse race, for example), are 3:5. That is the ratio of failure (white) to success (red).
Betting odds are stated in various ways. It is important to state which method is being used.