解:(1)
![](http://thumb.1010pic.com/pic5/latex/602.png)
x-
![](http://thumb.1010pic.com/pic5/latex/168.png)
x=2,
![](http://thumb.1010pic.com/pic5/latex/4457.png)
x=2,
![](http://thumb.1010pic.com/pic5/latex/4457.png)
x×
![](http://thumb.1010pic.com/pic5/latex/1047.png)
=2×
![](http://thumb.1010pic.com/pic5/latex/1047.png)
,
x=15,
(2)12-20%x=11.2,
12-20%x+20%x-11.2=11.2+20%x-11.2,
0.8=20%x,
20%x=0.8,
20%x÷20%=0.8÷20%,
x=4.
分析:(1)先把左边计算出来可得
![](http://thumb.1010pic.com/pic5/latex/4457.png)
x=2,再利用等式的性质两边同时乘
![](http://thumb.1010pic.com/pic5/latex/1047.png)
即可;
(2)根据等式的性质两边同时加上20%x-11.2,可得0.8=20%x,等式的两边交换位置后是20%x=0.8,再利用等式的性质,两边同时除以20%即可.
点评:此题考查了等式的性质的灵活应用.