Theoretical Probability

Sam ordered a large sixteen cut pizza. $\dfrac{1}{4}$ of the pizza has pepperoni and mushrooms, $\dfrac{1}{4}$ of the pizza has just pepperoni, $\dfrac{1}{4}$ of the pizza is plain, and $\dfrac{1}{4}$ has ham on it. If you were handed a random slice of pizza, what is the theoretical probability that you will receive a slice of pizza with meat on it?