3x= 120

The solution is x=40.

Later used: 180/40=4.5(h)

* * * Usage: 4.5+3=7.5 (high)

2) Solution: Suppose it takes x hours to process 180 pieces.

120/3= 180/x

Solution: x=4.5

* * * Usage: 3+4.5=7.5 (high)

Xiaohong is in the 25th place.

Xiaohua is in the sixth place.

There are two people: 25-6- 1= 18.