1, team a's efficiency:1÷16 =1/6, team b's efficiency: 1÷20= 1/20, which takes time.

The rest: 1- 1/4 = 3/4, and the number of days needed by Team A: 3/4 ÷116 =12 (days).

2, 9000 ÷ (1-10%)-9000 =1000 (yuan)

3.120 ÷ (1-20%) =150 (yuan)

96÷( 1-20%)= 120 (yuan)