Answer:
[tex]-5[/tex]
Step-by-step explanation:
[tex]3x+4=-5y+8\\9x+11y=-8[/tex]
Rearrange the first equation and substitute it into the second equation.
[tex]3x=-5y+8-4\\3x=-5y-4[/tex]
(as we want 9x instead of 3x we are going to multiply this equation by 3)
[tex]9x=-15y-12\\-15y-12+11y=-8\\-4y=4\\y=-1[/tex]
Rearrange the first equation and substitute in our y value to solve for x.
[tex]3x+4=-5(-1)+8\\3x=5+8-4\\3x=9\\x=3[/tex]
Hence
[tex]y-x=-1-4=-5[/tex]
