求未知数: (1)x+5/4x=27/16 (2)13/5:4=x:3.5.

问题描述:

求未知数:
(1)x+

5
4
x=
27
16

(2)1
3
5
:4=x:3.5.

(1)x+

5
4
x=
27
16

     (1+
5
4
)x=
27
16

          
9
4
x=
27
16

       
9
4
9
4
=
27
16
÷
9
4

             x=
27
16
×
4
9

             x=
3
4

(2)1
3
5
:4=x:3.5,
     1.6:4=x:3.5,
         4x=1.6×3.5,
         4x=5.6,
      4x÷4=5.6÷4,
          x=1.4.