1. Last year, a machine tool factory planned to produce 85 machine tools every month. In fact, 10 months completed the annual production plan. How many more machines are actually produced each month than originally planned?

85×12 ÷10-85 =17 (Taiwan Province)

2. A pool is 20 decimeters long, 18 decimeters wide and 54 decimeters high. Now the water level is 0/0/.5 decimeter away from the pool mouth. How many cubic decimeters of yellow sand should be poured in, and the water level just rises to the mouth of the pool?

20× 18× 1.5 = 540 (cubic decimeter)

★ (Smart people do this), the express train and the local train leave from A and B at the same time 14 hour. At this time, the local train is still 20 kilometers away from the midpoint. It is understood that this express train takes 20 hours to complete the journey. How many kilometers does the express train run per hour?

1/ 14- 1/20=3/ 140

1/20:3/ 140=7:3

20× 2 ÷ (7-3 )× (7+3) = 100 km