1, solution: let the number of days in arrangement A be x, and the number of days in arrangement B be 30-x; Let the maximum match be y, then there are:

A match: 120x/3=40x, b match:100 (30-x)/2 =1500-50x; If the matching is to be successful, it must be based on A, B has a surplus, and vice versa. (1) so there are 40x 16.6, x= 17, where y2 =1500-50x17 = 650 sets. Y 1 Compared with y2, A needs to arrange 17 days and B needs to arrange 13 days. ..

2. solution: let c and b meet for t minutes. It is easy to know that after C meets B, A and C leave for 10 minutes, which is the whole journey. Now we can know the complete length by finding the time when they met.

67.5t-60t=(60+75)× 10, and the total length is = (180+10 )× (60+75) = 25650m.

3. Solution:

( 1)、 100A

(2), 2(2000-30)

(3), 100A+2(2000-30A)=6640. Only five points. be very difficult for me