Let's see this original ewuation: [tex]x-y=11[/tex] 1) Substitute 4 in for x: [tex]4-y=11[/tex] 2)Subtract 4 from both sides. This cancels out four. [tex](4-4)-y=11-4[/tex] 3)Cancel: [tex]-y=7[/tex] 4)Multiply both sides by negative 1:[tex]-1*-y=11*-1 \\ y=-11[/tex]
