An all-you-can eat buffet attracts two type of customers. Regular customers value the buffet at $20 and eat $5 of food in cost 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 fr a buffet dinner, what is the restaurant's profit?
A) $2,500
B) $3,000
C) $4,500
D) $6,500