Back to basics - many probability problems can be simplified by considering the complement of what is asked - and then because those are mutually exclusive outcomes, the two probabilities add to 1 and so a subtraction gives the desired answer.
However, there are two difficulties with regard to this question.
We’re not told if this is with or without replacement
There probably is a mistake and two different colors may have been intended instead of “either a red marble or a red marble
