(1/2)х + (1/4)х + (1/7)х + 3 = x (1/2)х + (1/4)х + (1/7)х-x= -3 x(1/2+1/4+1/7 -1)= -3 x( (14+7+4 -28)/28)= -3 x(-3/28) = -3 x=28*3/3 x=28
Большое спасибо Юль .