During May Day, a company organized employees to travel to a certain place. In order to attract more customers, two travel agencies, A and B, respectively introduced group preferential measures to travel there. The preferential measures of a travel agency are: buy four full tickets and 50% off the original price; The preferential way of travel agency B is: 60% off the original price. It is understood that the original price of the two travel agencies is one yuan, and the quality of various services in the itinerary is the same. If you were the person in charge of this company, which travel agency would you choose?

Test analysis:

X people participated in the tour (1 minute)

When 4a+0.5(x-4)=0.6ax, x=20 (4 points).

When 4a+0.5a (x-4) > 0.6ax, x < 20 (6 points).

When 4a+0.5a (x-4) < 0.6ax, x > 20 (8 points).

A: When the number of participants is 20, choose one; When the number of participants is less than 20, choose B Travel Agency; When the number of participants is more than 20, choose a travel agency. (9 points) (The method is not unique)