Найдите корень уравнения : 1) 5(x-4)=x+8 2)9-7(x+3)=5-6x 3) (7x+9)+(11x-7)=8 4) 19,6+y=7(1,2-y) 5) 0,4(6-4y)=0,5(7-3y)-1,9

1)5(х-4)=х+8            2)9-7(х+3)=5-6х          3)(7х+9)+(11х-7)=8
    5х-20=х+8               9-7х-21=5-6х               7х+9+11х-7=8
    5х-х=8+20               -7х+6х=5-9+21             7х+11х=8-9+7
    4х=28                      х=17                             18х=6
    х=7                                                                х=1\3

4)19,6+у=7(1,2-у)       5)0,4(6-4у)=0,5(7-3у)-1,9
    19,6+у=8,4-7у            2,4-1,6у=3,5-1,5у-1,9
    у+7у=8,4-19,6            -1,6у+1,5у=3,5-1,9-2,4
    8у=-11,2                     -0,1у=-0,8
    у=-1,4                          у=8