5/4— 1= 1/4。
Number of storybooks in B: 4÷ 1/4= 16.
Number of storybooks in A: 16+4=20.
2. Xiao Fang has read two-thirds of the books, 30 pages more than the rest.
1—2/3= 1/3。
2/3— 1/3= 1/3。
30÷ 1/3=90 copies.
3. A set of desk 80 yuan, in which the price of the chair is 3/5 of that of the desk.
1+3/5=8/5。
Table: 80÷8/5=50 yuan.
Chair: 80-50 = 30 yuan.
4. Wang Gang has accomplished a number of tasks. It took him four days to finish the task originally planned for five days.
1÷4= 1/4。
1÷5= 1/5。
1/4— 1/5= 1/20。
5. There are 300 books on the shelves A and B. Take out 20 books from the shelf A and put them on the shelf B. At this time, the books on the shelf B are just 7/8 of the summer vacation.
1+7/8= 15/8。
300÷ 15/8= 160.
One original: 160+20= 180 copies.
B original: 300- 180 = 120 copies.