(0.5(x+y)/3z+0.5(x+y)/z=20
0.5(x+y) +3*0.5(x+y)=3z*20
0.5x+0.5y+3*0.5*(x+y)-3z*20=0
0.5x+0.5y+1.5*(x+y)-3z*20=0
0.5x+0.5y+1.5x+1.5y-3z*20=0
2x+0.5y+1.5y-3z*20=0
2x+2y-3z*20=0
2x+2y-60z=0
<span>x+y=30z</span>
<span>y=30z-x</span>
<u>-2х-122</u>=-12
9
-2х-122=-108
-2х=-108+122
-2х=14
х=-7
проверка <u>-2*(-7) -122 </u>=-108/9 =-12
9