如题所述
(x+15)/(x+100-15)=4/5
(x+15)/(x+85)=4/5
5(x+15)=4(x+85)
5x+75=4x+340
5x-4x=340-75
x=265
(x+15)/(x+85)=4/5
5(x+15)=4(x+85)
5x+75=4x+340
5x-4x=340-75
x=265
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第1个回答 2012-04-12
(x+15)/(x+100-15)=4/5
4(x+100-15)=5(x+15)
4x+340=5x+75
-x=-265
x=265
4(x+100-15)=5(x+15)
4x+340=5x+75
-x=-265
x=265
第2个回答 2012-04-12
简便方法:
(x+15)/(x+100-15)=4/5
(x+15)/(x+15+70)=4/5
(x+15)/70=4
x=265
(x+15)/(x+100-15)=4/5
(x+15)/(x+15+70)=4/5
(x+15)/70=4
x=265
第3个回答 2012-04-12
(x+15)/(x+100-15)=4/5
(x+15)/(x+85)=4/5
5*(x+15)=4*(x+85)
5x+75=4x+340
x=265
(x+15)/(x+85)=4/5
5*(x+15)=4*(x+85)
5x+75=4x+340
x=265
第4个回答 2012-04-12
x=265