Hope this helps. If you have any further question ask me in comment.
They would get approximately 3.33 ounces ( per person)
You have to keep order of operations in mind.
1. Take care of the parentheses; distribute.
-3+6x-3=-20-8x
Simplified: 6x-6=-20-8x
2. Isolate the x variable.
Add 8x to both sides and add 6 to both sides.
14x=-14
3. Solve for x.
Divide by 14 on both sides.
x=-1
I think the answer is the slope is -2 and the y-intercept is 12