Система5(х-3у)-26=2х+1, 3(-6у)+4=9у+19
5x-15y-26=2x+1; -18y+4=9y+19; 3x-15y=27; (:3) -27y=15; (:3) x-5y=9; -9y=5; x-5y=9; y=-0.5; x-5(-0.5)=9; y=-0.5; x+2.5=9; y=-0.5; x=6.5; y=-0.5.