解方程. 0.4x=22 3/8+x=2/5 x-1/5x=3/10.

问题描述:

解方程.
0.4x=22

3
8
+x=
2
5

x-
1
5
x=
3
10

(1)0.4x=22
    0.4x÷0.4=22÷0.4
            x=55;
(2)

3
8
+x=
2
5

 
3
8
+x-
3
8
=
2
5
-
3
8

       x=
1
40

(3)x-
1
5
x=
3
10

      
4
5
x=
3
10

   
4
5
5
4
=
3
10
×
5
4

         x=
3
8