For example, the table shows the prices of several tickets published on the official ticketing website of the Shanghai World Expo. Before China International Import Expo(CIIE), Xiao Li spent 4200 yuan as the fund for booking tickets. (1) Book X tickets for three days and Y tickets for seven days.

Judging from the meaning of the title, 400 x+900 y = 4200 x+y = 8,

X = 6y = 2，

A: Six for three days and three for seven days.

(2) Yes, for the following reasons:

If you book a regular ticket for a specified day and a three-day ticket for B, then the number of votes for seven days will be (10-a-b).

200 A+400 B+900( 10-A-B)= 4200。

7a+5b=48，

The solution is b=48? 7a5。

∵a and B are positive integers,

When a=4 and b=4,

∴ 10-4-4=2.

Book four ordinary tickets, four three-day tickets and two seven-day tickets on the specified date.

Xiao Li's idea can come true.