Final answer:
To represent the number of large drinks, use the expression 'm'.
Step-by-step explanation:
To write an expression representing the number of large drinks, let's define 'm' as the number of large drinks. Since the total number of medium and large drinks sold is 325, we can set up the equation:
m + (325 - m) = 325
Simplifying this equation, we get:
m + 325 - m = 325
325 = 325
Therefore, the expression to represent the number of large drinks is 'm'.