1.8x÷1.8=0.972÷1.8

X=0.54

(30)x÷0.756=90

x÷0.756×0.756=90×0.756

X=68.04

(31)0.1(x+6)=3.3×0.4

0.1x+0.6=1.32

0.1x+0.6-0.6=1.32-0.6

0.1x=0.72

0.1x÷0.1=0.72÷0.1

X=7.2

(32)(27.5-3.5)÷x=4

24÷x=4

x=24÷4

X=6

(33)9x-40=5

9x-40+40=5+40

9x=45

9x÷9=45÷9

X=5

(34)x÷5+9=21

x÷5+9-9=21-9

x÷5=12

x÷5×5=12×5

X=60

(35)48-27+5x=31

5x+21-21=31-21

5x=10

5x÷5=10÷5

X=2

(36)10.5+x+21=56

x+31.5-31.5=56-31.5

x=24.5

(37)x+2x+18=78

3x+18-18=78-18

3x=60

3x÷3=60÷3

X=20

(38)(200-x)÷5=30

(200-x)÷5×5=30×5