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(2003•龙湖区)求未知数X.(1)0.2X+0.4×3=9.4(2)12:15=0.25:X.

题目详情
(2003•龙湖区)求未知数X.
(1)0.2X+0.4×3=9.4
(2)
1
2
1
5
=0.25:X.
▼优质解答
答案和解析
(1)0.2X+0.4×3=9.4,
        0.2X+1.2=9.4,
    0.2X+1.2-1.2=9.4-1.2,
            0.2X=8.2,
       0.2X÷0.2=8.2÷0.2,
               X=41;

(2)
1
2
1
5
=0.25:X,
       
1
2
X=
1
5
×0.25,
       
1
2
X=0.05,
   
1
2
1
2
=0.05÷
1
2

          X=0.1.