Answer:
[tex]8x=32\\2y=-24[/tex]
Step-by-step explanation:
When solving for 1 variable, set the other to 0 and solve.
[tex]3x-y(0)=12\\3x=12\\x=4\\4*8=32\\8x=32\\\\3(0)-y=12\\-y=12\\y=-12\\-12*2=-24\\2y=-24[/tex]