I don't know what the "lowest y-intercept means" so if you can reiterate and clarify I'd appreciate it, but if you understand what you're looking for then I assume that a graph would be helpful. An online useful graphing site I like is desmos. Hope I helped.
Answer:
x=16, y=-4
Step-by-step explanation:
-1(x-y=12)
x+7y=-20
-x+y=-12
x+7y=-20
8y=-32
y=-4
x-4=12
x=16
It is 236. Happy to help (:
