Question:
A card is drawn at random from a standard 52-card deck.  What is the probability that it is an odd number (3,5,7,9) or a $\spadesuit$ (or both)?

Answer:
There are 16 odd-numbered cards, namely 4 suits for each of the 4 odd digits. There are 13 $\spadesuit$s, but 4 of these we already counted among the odd-numbered cards.  So the total number of cards that are odd or a $\spadesuit$ is $16+(13-4)=25$, and the probability is $\boxed{\dfrac{25}{52}}$.