General equation: The general equation is very simple. I'll help you calculate the specific figures. Addition, subtraction, multiplication and division should be the opposite.

Example:

x+3=5

Solution: x+3-3=5-3

x=2

x-3=2

Answer: x-3+3=2+3.

x=5

3x=6

Solution: 3x÷3=6÷3

x=2

x÷3=3

Solution: x÷3×3=3×3

x=9

Special equation: don't make trouble with special equations, add, subtract, multiply and divide with unknowns, and the multiplication becomes general.

Example:

20-x=9

Solution: 20-x+x=9+x

20=9+x

9+x=20

9+x-9=20-9

x= 1 1

2. 1÷x=3

Solution: 2. 1÷x×x=3×x

2. 1=3×x

3×x=2. 1

3×x÷3=2. 1÷3

x=0.7

A slightly more complicated equation: a little more complicated, a little farther away.

( 1)ax+b=c

ax-b=c

For example: 3x+4=40

Solution: 3x+4-4=40 -4

3x=36

3×3 = 36×3

x= 12

3x-6=9

Solution: 3x-6+6=9+6.

3x= 15

3×3 = 15×3

x=5

(2)a(x-b)=c

a(x+b)=c

Example:

2(x- 18)= 16

Solution: 2(x- 18)÷2= 16÷2.

x- 18=8

x- 18+ 18=8+ 18

x=26

2(x- 18)= 16

Solution: 2x-36= 16

2x-36+36= 16+36

2x=52

x=26