Question

Part 1:

Answer 1

Here are my answers to the given questions above:
Part 1. Here is my example of a real life scenario that describes what is happening. Let us say, I have 2 cookies and the bottle of milk costs 11 dollars, and 3 cookies and 4 bottles of milk cost 24 dollars.
Part 2. 
y=11-2x
3x+4(11-2x)=24
3x+44-8x=24
-5x=-20
x=4
y=11-8
y=3
Therefore, each cookie costs 4 dollars, and a bottle of milk costs 3 dollars.
Hope this answer helps. Let me know if you need more help next time.