Question

解方程． （x+1.5）×2=7 1.2×4-x=2.1 2.7x-1.6=38.9  x÷4.5=20．

Answer 1

①（x+1.5）×2=7
   （x+1.5）×2÷2=7÷2
            x+1.5=3.5
        x+1.5-1.5=3.5-1.5
                 x=2

②1.2×4-x=2.1
     4.8-x=2.1
   4.8-x+x=2.1+x
      2.1+x=4.8
 2.1+x-2.1=4.8-2.1
          x=2.7

  ③2.7x-1.6=38.9 
2.7x-1.6+1.6=38.9+1.6 
         2.7x=40.5
   2.7x÷2.7=40.5÷2.7
           x=15

   ④x÷4.5=20
x÷4.5×4.5=20×4.5
          x=90