7x÷7=21÷7 X=3 (147) X-5.7=2.15 x=5.7+2.15 X=7.85 (148) 5X-2X=18 3x=18 3x÷3=18÷3 X=6 (149) 3X +0.5=5 3x+0.5-0.5=5-0.5 3x=4.5 3x÷3=4.5÷3 X=1.5 (150) 3.5×2= 4 x 4x=7 4x÷4=7÷4 X=1.75 (151) 26×1.5= 2x 2x=39 2x÷2=39÷2 X=18

(152) 0.5×16―16×0.1=4x 4x=6.4 4x÷4=6.4÷4 X=1.6 (153) 9.26－X=0.402 X=9.26-0.402 X=8.858 (154) 36.9÷X=0.3 X=36.9÷0.3 X=123 (155) X÷0.5=2.6 X=0.5×2.6 X=1.3 (156) 93－5x＝80 93-5X+5X=80+5X 5X+80-80=93-80 5X=13 5X÷5=13÷5 X=2.6 (157) 180-6x＝54 180-6X+6X=54+6X 6X+54-54=180-54

6X=126 6X÷6=126÷6 X=21 (158) 9＋4x＝40 4X+9-9=40-9 4X=31 4X÷4=31÷4 X=7.75

(159) 0.2x－0.4＋0.5＝3.7 0.2X-0.5+0.5-0.4+0.4=3.7-0.5+0.4 0.2X=3.6 0.2X÷0.2=3.6÷0.2 X=18 (160) 9.4x－0.4x＝16.2 9X=16.2 9X÷9=16.2÷9 X=1.8 (161) 92－4x＝20 92-4X+4X=20+4X 4X+20-20=92-20 4X=72 4X÷4=72÷4 (162) X=18 (163) 7x÷6=1.4 7x÷6×6=1.4×6 7X=8.4 7X÷7=8.4÷7 X=1.2 (163) 16x＋34x=1 50X=1 50X÷50=1÷50 X=0.02 (164) 18x－14x=12 4X=12 4X÷4=12÷4 X=3 (165) 3 x－42÷14=15 3X-3=15 3X-3+3=15+3 3X=18 3X÷3=18÷3 X=6

(166) 12＋4x=56

17

4X+12-12=56-12 4X=44 4X÷4=44÷4 X=11

(167) 22－14x=12 22-14X+14X=12+14X 14X+12-12=54-12 14X=42

14X÷14=42÷14 X=3

(168) X+8.3=10.7

X=10.7-8.3 X=2.4

(169) 5x ＝30

5X÷5=30÷5 X=6

(170) x-5.6=9.4

X=5.6+9.4 X=15

(171) x÷0.8=90

X=0.8×90 X=72

(172) 3x－8＝16

3X-8+8=16+8 3X=24 3X÷3=24÷3 X=8

(173) 3x+9=27

3X+9-9=27-9 3X=18 3X÷3=18÷3 X=6

(174) 5.3+7x=7.4 7X+5.3-5.3=7.4-5.3 7X=2.1 7X÷7=2.1÷7 X=0.3 (175) 3x÷5=4.8 3X=4.8×5 3X=24 3X÷3=24÷3 X=8

(176) X-0.8X=6

0.2X=6

0.2X÷0.2=6÷0.2

X=30

(177) 12x+8x=4.8

20X=4.8 20X÷20=4.8÷20 X=24

(178) 7(x-2)=49

7X-14=49 7X-14+14=49+14

7X=63 7X÷7=63÷7 X=9

(179) 4×8+2x=36 2X+32=36 2X+32-32=36-32 2X=4 2X÷2=4÷2

X=2

(180) (x-2)÷3=7 X-2=3×7 X-2=21 X=23

(181) x÷5+9=21 X÷5=21-9 X÷5=12 X=12×5 X=60

(182) (300-x)÷5=30 300-X=30×5

300-X=150 X=300-150 X=150

(183) 91÷x ＝1.3 X=91÷1.3 X=70

(184) 41-3x=17 41-3X+3X=17+3X 3X+17-17=41-17 3X=24 3X÷3=24÷3 X=8

18

19