Can you please explain how you get the answer to this problem?

An all-you-can-eat buffet attracts two types of customers. Regular customers value the buffet at $20

and eat $5 of food in costs to the restaurant. Hungry customers value the buffet at $40 and eat $10 of

food. If there are 100 of each type in the market for a buffet dinner, what is the restaurant's profit?

a. $2,500

b. $3,000

c. $4,500

d. $6,500

Answer: B