1)(20.2-0.6х)*5.4+21.42=114.3
109,08-3,24х+21,42=114,3
-3,24х=114,3-109,08-21,42
-3,24х=-16,2
-х=-5
х=5
2)(6.9х-4.7х-2х-13.8)/4=21.6
6,9х-4,7х-2х-13,8=21,6*(-4)+13,8
6,9х-4,7х-2х=-86,4+13,8
0,2х=-72,6
х=-363
3)1.5*(2.4+1.2х)+0.9*(0.7-1.2)=51.12
3,6+1,8х+0,63-1,08=51,12
1,8х=51,12-3,6-0,63+1,08
1,8х=47,97
х=26,65