Final answer:
20 customers ordered mushrooms on their pizza but no pepperoni, calculated by subtracting the number of customers who ordered both toppings from those who ordered mushrooms.
Step-by-step explanation:
To determine how many customers ordered mushrooms but no pepperoni on their pizza, we must subtract the number of customers who ordered both from the total number of customers who ordered mushrooms.
According to the data given:
To find the number of customers who ordered mushrooms only, we subtract those who ordered both from the total that ordered mushrooms:
Mushrooms only = Total mushrooms - Both mushrooms and pepperoni
Mushrooms only = 80 - 60
Mushrooms only = 20
Therefore, 20 customers ordered mushrooms on their pizza but did not order pepperoni.