Solution: 2 1+7x- 12=5x+88.

7x-5x=88-2 1+ 12

2x=79

X=39.5

2 .6.90÷x-90÷3x=3

Solution: 69/ 10x-900/3x=3.

207/30x-900/30x=90x/30x

-693=90x

x=-7.7

3 .2.4÷5x-2.4÷6x= 1.6

Solution: (2.4x6-2.4x5) /30x= 1.6

2.4/30x= 1.6

2.4= 1.6x30x

2.4 = 48 times

X=0.05

4 .(9.7+2x)÷2=(5.5+5x)÷3

Solution: 29.1+6x =11+10x.

18. 1=4x

X=4.525

Second, solve the application problems by column equations.

1. In two fertilizer warehouses, the fertilizer in warehouse A is 2.4 times that in warehouse B, and the fertilizer in warehouse B is 44.8 tons less than that in warehouse A.. How many tons of chemical fertilizer are stored in warehouse A and warehouse B respectively?

Solution:

Suppose: B has x tons of inventory, then A has 2.4x tons of inventory.

2.4x-x=44.8

1.4x=44.8

x=32

2.4x32=76.8

76.8 tons of A shares and 32 tons of B shares.

2. The goods in warehouse A are 560 tons more than those in warehouse B. If two warehouses carry 9 tons of goods at the same time, the remaining goods in warehouse A are three times that in warehouse B. How many tons of goods were there in warehouse A and warehouse B?

Solution: If warehouse A has X tons and warehouse B has x-560 tons.

x-3=3x(x-560-3)

x-3=3x- 167 1

2x= 167 1-3

x=834

834 - 560=274

The original 834 tons in warehouse A and 274 tons in warehouse B..

The deposits of Party A and Party B are equal. Later, A took out 400 yuan and B deposited it in 300 yuan. At this time, B's deposit is three times that of A. How much did they have?

Solution: Set a deposit of X yuan.

3x(x-400)=x+300

3x- 1200=x+300

x=750

The original deposit of Party A and Party B is 750 yuan.

There are two counters in the video store. There are fewer tapes in counter A than in counter B. 120 ... If two counters each sell 164 boxes, the remaining amount of counter B is three times that of counter A. How many tapes are there in each of the two counters?

Solution: If the original X box of counter A is set, the original X box of counter B is x+ 120.

3x(x- 164)= x+ 120- 164

x=448

There are 448 boxes at counter A and 448+ 120=560 boxes at counter B.

5. The school bought three sets of desks and chairs ***690 yuan, 1 A desk is more expensive than a chair, 80 yuan. How much is a table and a chair?

Solution: Set up a table X yuan and a chair x-80 yuan.

3x[x+(x-80)]=690

x= 155

X-80= 155-80=75 yuan.

A table 155 yuan a chair 75 yuan.

6. The average selling price of the three vegetables is around 0.8 yuan. It is known that class A vegetables are more expensive than class B vegetables per kilogram, 0.4 yuan. C food is 0. 1 yuan cheaper. What's the price of these three vegetables per kilogram?

Solution: If the price of dish B is X yuan, then the price of dish A is x+0.4 yuan and the price of dish C is 0.8-0. 1=0.7 yuan.

(x+0.4+x+0.7)/3=0.8

x=0.65

0.65+0.4= 1.05 yuan

The price of a dish is 1.05 yuan, the price of b dish is 0.65 yuan, and the price of c dish is 0.7 yuan.