People's Education Press has 26 pages of answers to exercises in each class of sixth grade primary school mathematics (there must be formulas, numbers and equations).

1. solution: make this bag of oranges weigh x kilograms.

( 1-3/5)x=6

2/5 x=6

x=6/ 2/5

x= 15

A: This bag of oranges used to weigh 15 Jin.

2. Solution: Set up a commissary to buy back X Jin of flour.

x( 1+ 1/5)=360

x 6/5=360

x=360/ 6/5

x=300

Answer: I bought 300 Jin of flour in the canteen.

3. Solution: Let the ocean area be about x billion square kilometers.

5/ 12x=2/3

x=2/3 / 5/ 12

x=8/5

A: The ocean area is about 850 million square kilometers.

4. Solution: Suppose the original scheme costs X million yuan.

( 1+ 1/8)x=720

9/8x=720

x=720/ 9/8

x=640

A: The original plan was to spend 6.4 million yuan.

5. solution: the original price of this repeater is x yuan.

( 1- 1/6)x= 100

5/6x= 100

x= 100/ 5/6

x= 120

A: The original price of this repeater is 120 yuan.

6. Solution: Suppose there are X science books.

x+ 1/3x=80

4/3x=80

x=80/ 4/3

x=60

80-60=20 (Ben)

A: There are 60 science books and 20 fairy tales.