a business has $15,000 to spend on airline tickets to travel to a conference. it wants 27 of its employees to attend. the business wants to buy as many business-class seats as possible. the business-class seats cost $700. the economy-class seats cost $375. create a system of equations that models how many of each type of ticket the business should purchase.

a 700x + 375y = 27
x + y = 15,000

b x + 375y = 15,000
700x + y = 27

c 700x + y = 15,000
x + 375y = 27

d 700x + 375y = 15,000
x + y = 27