1. It takes 0. 1 cm to saw a 27.9 cm long piece of wood into 2.9 cm and 4.9 cm pieces. How many pieces of wood of two specifications can be sawed to minimize waste? (List the calculations of various schemes)

2. Pears with100kg have a water content of 90%. After storage for one week, the moisture content has dropped to 80%. How many kilograms is this batch of fruit now?

The circumference of rectangle is 88 cm. If the width increases by 25%, the length decreases by one seventh, and the circumference remains the same, how about the length of S =?

4. A two-story bookshelf with 40% books on it. If you put 48 books from the upper level to the lower level, the books from the lower level account for 75% of the total. How many books are there on this shelf?

5. Warehouse A has 120 tons of grain, and now 15% is transferred from warehouse A to warehouse B. At this time, warehouse A has 22 tons more than 80% of warehouse B. How many tons of grain does warehouse B have now?

6. The mid-term sports achievement rate of a school is 55%, and the final freshmen are 130, accounting for 80% of the total number. How many people are still not up to standard?