1. The surface area of a cube is 54 square decimeters. If the edge length is reduced by 1 decimeter, the volume will be reduced by () cubic decimeter 2. It takes 20 hours for Master Li to make a batch of parts, and 30 hours for his apprentice to do it alone. How many hours can master apprentice cooperation complete two-thirds of this batch of parts? 3. There is a cone with a volume of 157 cubic centimeters and a bottom radius of 2 centimeters. What is the height of the cone? 4. A factory has 36 tons of coal, which has been burned for 12 days, with an average of 1.2 tons of coal per day. How many days can the remaining coal be burned

1. The surface area of a cube is 54 square decimeters. If the edge length is reduced by 1 decimeter, the volume will be reduced by () cubic decimeter 2. It takes 20 hours for Master Li to make a batch of parts, and 30 hours for his apprentice to do it alone. How many hours can master apprentice cooperation complete two-thirds of this batch of parts? 3. There is a cone with a volume of 157 cubic centimeters and a bottom radius of 2 centimeters. What is the height of the cone? 4. A factory has 36 tons of coal, which has been burned for 12 days, with an average of 1.2 tons of coal per day. How many days can the remaining coal be burned

1. The surface area of a cube is 54 square decimeters. If the edge length is reduced by 1 decimeter, the volume will be reduced by (30) cubic decimeters. 2. To process a batch of parts, Master Li takes 20 hours to do it alone, and his apprentice takes 30 hours to do it alone. The apprentice can complete two-thirds of the batch of parts in a few hours