1. Solution: Let the length of nail edge be x decimeter, then the length of nail edge is 2X decimeter. According to the question, it means: x 3+(2x) 3 = 27. Solve it, that is: x 3 = 3 cubic decimeters; Then: b square volume: 27-3=24 cubic decimeters. That is, the volumes of two cubes A and B are 3 cubic decimeters and 24 cubic decimeters respectively.

2. Let the base angle be x and the top angle be 2x.

2x+x+x= 180

x=45

That is, the base angle is: 45 and the top angle is: 90.

3. There are as many completed tasks as the rest, that is, 1/2.

* * * Yes:15/(1/2-1/3) = 90.

4. Solution: In the past, bookcase B had 5X books and bookcase A had 2X books.

(2X+360):(5X)=5:8

Internal product = external product

16X+2880=25X

9X=2880

X=320

B There are 5X books on the shelf.

320*5= 1600 (Ben)