问题
解答题
解比例或方程.
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答案
(1)
=x 25
,1.2 75
75x=25×1.2,
75x÷75=30÷75,
x=0.4;
(2)
:2 3
=x:9,12 13
x=12 13
×9,2 3
x÷12 13
=6÷12 13
,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.