1. Equation: 9-x = 3,80 ÷ 4 = 20,7y = 63,20+30 = 50, y+17y=63 38,54 ÷ x = 9;

Equation: 9-x=3, 7y=63, y+ 17=38, 54÷x=9.

2.30+x = 80； 4x = 80；

3.52+x = 1 10；

4.x+ 10=50，3 x=20+70 .

1.-20; +54,+54。

2. Solution: x=70+35

x= 105

Solution: x=84-48

x=36

Solution: x=50+50

x= 100

Solution: x= 100-27

x=73

Solution: x=70+20

x = 90°

Solution: x=9-3

x=6

3.x +20= 100

Solution: x= 100-20

x =80

4.2; 5。

1. Subtract 36 from both sides of the equal sign.

x =64-36

x=28

Add 0.8 to both sides of the equal sign.

x = 1.9+0.8

x=2.7

2. Solution: x=490-240

x=250

Solution: x=5.5-0.7

x=4.8

Solution: x=95-69

x=26

Solution: x=47+47

x=94

Solution: x= 12-9.6

x=2.4

Solution: x= 1.4+0.78

x=2. 18

3.( 1)x=32，(2) x=20，(3) x=3

4.x+20= 100+ 10

Solution: x= 100+ 10-20.

x = 90°

5.5+x= 10

Solution: x= 10-5.5

x=4.5

1.×,√,×,√;

2.( 1) solution: x=6.3-3.8

x=2.5

(2) solution: x=7.2-4.8

x=2.4

(3) solution: x=4+ 1.8

x=5.8

(4) solution: x=7.9+2.6

x= 10.5

(5) solution: x=6.5+3.2

x=9.7

(6) solution: x=2.3-0.46

x= 1.84

3.( 1)x +36=45

Solution: x=45-36

x=9

(2)x -2=98 (or x -98=2)

Solution: x=98+2

x= 100

(3) x -45= 128

Solution: x= 128+45