解下列方程．①3x+20=110②2.6x-1.8x=7.2③8x+4.8=8.8④x-（89+19）=1⑤x-0.5x=5⑥3.2x-1=63⑦18.6+4.2x=31.2⑧12x÷3=16⑨（x-32）×5=115

Question

解下列方程． ①3x+20=110	②2.6x-1.8x=7.2	③8x+4.8=8.8
④x-（(8)/(9)+(1)/(9)）=1	⑤x-0.5x=5	⑥3.2x-1=63
⑦18.6+4.2x=31.2	⑧12x÷3=16	⑨（x-32）×5=115

Answer 1

①3x+20=110 
   3x+20-20=110-20
         3x=90
      3x÷3=90÷3
          x=30

②2.6x-1.8x=7.2
       0.8x=7.2
  0.8x÷0.8=7.2÷0.8
          x=9

③8x+4.8=8.8
 8x+4.8-4.8=8.8-4.8
         8x=4
      8x÷8=4÷8
          x=0.5

④x-（(8)/(9)+(1)/(9)）=1
         x-1=1
       x-1+1=1+1
           x=2

⑤x-0.5x=5
     0.5x=5
0.5x÷0.5=5÷0.5
        x=10

⑥3.2x-1=63
 3.2x-1+1=63+1
     3.2x=64
3.2x÷3.2=64÷3.2
        x=20

⑦18.6+4.2x=31.2
18.6+4.2x-18.6=31.2-18.6
          4.2x=12.6
     4.2x÷4.2=12.6÷4.2
             x=3

⑧12x÷3=16 
12x÷3×3=16×3
      12x=48
  12x÷12=48÷12
        x=4

⑨（x-32）×5=115
（x-32）×5÷5=115÷5
         x-32=23
      x-32+32=23+32
            x=55