1. for the following system, if you isolated x in the second equation to use the substitution method, what expression would you substitute into the first equation? 2x + y = 8 −x − 3y = −12 3y + 12 −3y + 12 3y − 12 −3y − 12 2. check my answer for the picture question

A is right hope this helps you can i get brailylist

2x + y = 8
−x − 3y = −12 → - x = 3.y - 12 → x = -3.y + 12. So I will substitude in the 1st equation, x by  -3.y + 12 (2nd answer)

2) you follow the same logic as previously done
and you will find 2x+4y ≥ -16. 
Isolate y → 4y ≥ - 2x - 16→→y ≥ - x/2 -4
1st you notice that it's a straight line (and not - - - ), then the equation should have ≥ (and not > )

2nd) It's decreasing that means a<0 (a= - 1/2)
3rd) for x = 0 ; y = -4
All that satisfies the equation y ≥ - x/2 -4 OR 2x+4y ≥ -16 (last answer)