2. If [tex]y=2x+11[/tex], then in the second equation we'd get
[tex]y+x=5\implies(2x+11)+x=5\implies3x+11=5\implies3x=-6\implies x=-2[/tex]
Then we get [tex]y=2(-2)+11=7[/tex].
3. If [tex]-5x+y=-1[/tex], then [tex]y=5x-1[/tex], and substituting this into the second equation gives
[tex]y-4x=-3\implies(5x-1)-4x=-3\implies x-1=-3\implies x=-2[/tex]
which gives
[tex]y=5(-2)-1=-11[/tex]
