3х(3+12)-42(х+2х)=7х+6(3-4х)+12
9х+36-42х-84х=7х+18-24х+12
9х-42х-84х-7х+24х=18+12-36
-100х=-6
х=0,06
3х(3+12)-42(х+2х)=7х+6(3-4х)+12
9х+36-42х-84х=7х+18-24х+12
9х-42х-84х-7х+24х=18+12-36
-100х=-6
х=0,06