Question

解方程．5x+28=71  ...

解方程．5x+28=71 8.7-1.2x=3.9 8x-2.6x=37.80.75x-0.95×4=8.5 2（x-3）=5.8 8x-2.6=37.8

Answer 1

①5x+28=71
  5x+28-28=71-28
        5x=43
     5x÷5=43÷5
         x=8.6

②8.7-1.2x=3.9  
8.7-1.2x+1.2x=3.9+1.2x
          8.7=3.9+1.2x
 3.9+1.2x-3.9=8.7-3.9
         1.2x=4.8
    1.2x÷1.2=4.8÷1.2
            x=4 

③8x-2.6x=37.8
     5.4x=37.8
5.4x÷5.4=37.8÷5.4
        x=7

④0.75x-0.95×4=8.5  
      0.75x-3.8=8.5 
 0.75x-3.8+3.8=8.5+3.8
         0.75x=12.3
   0.75x÷0.75=12.3÷0.75
             x=16.4

⑤2（x-3）=5.8 
2（x-3）÷2=5.8÷2
        x-3=2.9
      x-3+3=2.9+3
          x=5.9

⑥8x-2.6=37.8
8x-2.6+2.6=37.8+2.6
        8x=40.4
     8x÷8=40.4÷8
         x=5.05