求未知数x. 1/4:1.4=3/4:x 120×40%+120×9/20+x=120.

问题描述:

求未知数x.

1
4
:1.4=
3
4
:x
120×40%+120×
9
20
+x=120.

(1)

1
4
:1.4=
3
4
:x,
            
1
4
x=1.4×
3
4

         
1
4
x÷
1
4
=1.4×
3
4
÷
1
4

               x=4.2;
(2)120×40%+120×
9
20
+x=120,
                 48+54+x=120,
                   102+x=120,
               102+x-102=120-102,
                       x=18;