1)5(х-4)=х+8
5х-20=х+8
5х=х+20+8
5х=х+28
5х-х=28
4x=28 |:4
х=7
2)9-7x-21=5-6x
-7x+6x=5-9+21
-x=17
x=-17
3)(7x+9)-(11x-7)=8
7x+9-11x+7=8
-4x=-8
x=2
1)5(х-4)=х+8
5х-20=х+8
5х=х+20+8
5х=х+28
5х-х=28
4x=28 |:4
х=7
2)9-7x-21=5-6x
-7x+6x=5-9+21
-x=17
x=-17
3)(7x+9)-(11x-7)=8
7x+9-11x+7=8
-4x=-8
x=2