1) 3x-100=20;
3x=20+100;
3x=120;
x=40.
2)200-5x=40;
-5x=40-200;
-5x=-160;
x=32.
3)8x+100=140;
8x=140-100;
8x=40;
x=5.
4)(2x-10)*5=25;
2x*5-10x*5=25
10x-50=25;
10x=25+50;
10x=75;
x=75:10=7,5.
5)11*(30-4x)=22;
11*30-11*(-4x)=22
330-44x=22;
330-44x-22=0;
308-44x=0
-44x=-308;
x=-308:(-44)=7