求未知数. 3/20:6=6.5x 3/4x-1.4=3.6+2/3x.

问题描述:

求未知数.

3
20
:6=
6.5
x

3
4
x-1.4=3.6+
2
3
x.

(1)

3
20
:6=
6.5
x

          
3
20
x=6×6.5,
          
3
20
x=39,
      
3
20
20
3
=39×
20
3

             x=260;
(2)
3
4
x-1.4=3.6+
2
3
x,
 
3
4
x-1.4
2
3
x=3.6+
2
3
x
2
3
x,
   
1
12
x-1.4=3.6,
1
12
x-1.4+1.4=3.6+1.4,
        
1
12
x=5,
   
1
12
x×12=5×12,
           x=60.