问题 解答题
解比例或方程.
x
25
=
1.2
75
2
3
12
13
=x:9
1-25%x=0.545%x+x=29.
答案

(1)

x
25
=
1.2
75

          75x=25×1.2,

      75x÷75=30÷75,

            x=0.4;

(2)

2
3
12
13
=x:9,

       

12
13
x=
2
3
×
9,

  

12
13
x÷
12
13
=6÷
12
13

          x=6.5;

(3)1-25%x=0.5,

1-25%x+25%x=0.5+25%x,

      1-0.5=0.5+25%x-0.5,

   0.5÷25%=25%x÷25%,

          x=2;

(4)45%x+x=29,

      1.45x=29,

1.45x÷1.45=29÷1.45,

          x=20.

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