解方程 x/8=0.240.6 1.24×4-7x=3/5 x-30%x=50%x+12.

问题描述:

解方程

x
8
=
0.24
0.6

1.24×4-7x=
3
5

x-30%x=50%x+12.

(1)

x
8
0.24
0.6

        0.6x=8×0.24,
   0.6x÷0.6=1.92÷0.6,
           x=3.2;
(2)1.24×4-7x=
3
5

        4.96-7x=
3
5

     4.96-7x+7x=
3
5
+
7x,
         
3
5
+7x=4.96,
      
3
5
+7x-
3
5
=4.96-
3
5

          7x÷7=4.36÷7,
              x=
109
175

(3)x-30%x=50%x+12,
x-30%x-50%x=50%x+12-50%,
       0.2x=12,
  0.2x÷0.2=12÷0.2,
          x=60.