5/x+9/x+9/( 1.5x) = x = 20， 1.5x = 30。

Therefore, it takes 20 days and 30 days for Party A and Party B to complete the renovation project alone.

(2) If the decoration team is set up for y days, Party A will complete y/20 of the project quantity, and Party B will complete the remaining (20-y)/20, and Party B needs to carry out [30(20-y)]/20 days of construction, that is, 4000 Y+2000 [30 (20-Y)]/20.

The solution is y≤ 10.

Therefore, a decoration team can work for 10 days at most.

(3) The project needs to be completed within 65,438+04 days, including the first 4 days. After four days of cooperation between the two teams, the total amount is (4/20+4/30)= 1/3. If Team A is assigned to transfer m people, the remaining players of Team A will complete (12-m)/ (.

Therefore, Team A can deploy up to 4 people, and the project can be completed within 14 days.