解:(1)x-
![](http://thumb.1010pic.com/pic5/latex/96.png)
x=3.6,
![](http://thumb.1010pic.com/pic5/latex/365.png)
x=3.6,
![](http://thumb.1010pic.com/pic5/latex/365.png)
x÷
![](http://thumb.1010pic.com/pic5/latex/365.png)
=3.6
![](http://thumb.1010pic.com/pic5/latex/157681.png)
,
x=4.8;
(2)
![](http://thumb.1010pic.com/pic5/latex/1180.png)
÷x=
![](http://thumb.1010pic.com/pic5/latex/1180.png)
÷x×x=
![](http://thumb.1010pic.com/pic5/latex/35.png)
×x,
![](http://thumb.1010pic.com/pic5/latex/1180.png)
![](http://thumb.1010pic.com/pic5/latex/182843.png)
=
![](http://thumb.1010pic.com/pic5/latex/35.png)
x
![](http://thumb.1010pic.com/pic5/latex/182843.png)
,
x=4
![](http://thumb.1010pic.com/pic5/latex/597.png)
;
(3)
![](http://thumb.1010pic.com/pic5/latex/53135.png)
=9.1,
![](http://thumb.1010pic.com/pic5/latex/53135.png)
×7=9.1×7,
x=63.7;
(4)
![](http://thumb.1010pic.com/pic5/latex/365.png)
:x=15:20,
15x=20×
![](http://thumb.1010pic.com/pic5/latex/365.png)
,
15x÷15=15÷15,
x=1.
分析:(1)先化简方程,再依据等式的性质,方程两边同时除以
![](http://thumb.1010pic.com/pic5/latex/365.png)
求解,
(2)依据等式的性质,方程两边同时乘x,再同时除以
![](http://thumb.1010pic.com/pic5/latex/35.png)
求解,
(3)依据等式的性质,方程两边同时乘7求解,
(4)先根据比例基本性质,两内项之积等于两外项之积,化简方程,再依据等式的性质,方程两边同时除以15求解.
点评:本题主要考查学生运用等式的性质,以及比例基本性质解方程的能力.