c = cost per pound of chocolate chips
w = cost per pound of walnuts.
![\bf \stackrel{\textit{3 lbs of "c"}}{3c}+\stackrel{\textit{5 lbs of "w"}}{5w}~~=~~\stackrel{\textit{costs}}{15} \\\\\\ \stackrel{\textit{12 lbs of "c"}}{12c}+\stackrel{\textit{2 lbs of "w"}}{2w}~~=~~\stackrel{\textit{costs}}{33} \end{cases}\qquad \impliedby \textit{let's use elimination} \\\\[-0.35em] ~\dotfill\\\\ \begin{array}{llccccccl} 3c+5w=15&\times (-4)\implies &-12c&+&-20w&=&-60\\ 12c+2w=33&&12c&+&2w&=&33\\ \cline{3-7}\\ &&0&&-18w&=&-27 \end{array}](https://tex.z-dn.net/?f=%5Cbf%20%5Cstackrel%7B%5Ctextit%7B3%20lbs%20of%20%22c%22%7D%7D%7B3c%7D%2B%5Cstackrel%7B%5Ctextit%7B5%20lbs%20of%20%22w%22%7D%7D%7B5w%7D~~%3D~~%5Cstackrel%7B%5Ctextit%7Bcosts%7D%7D%7B15%7D%20%5C%5C%5C%5C%5C%5C%20%5Cstackrel%7B%5Ctextit%7B12%20lbs%20of%20%22c%22%7D%7D%7B12c%7D%2B%5Cstackrel%7B%5Ctextit%7B2%20lbs%20of%20%22w%22%7D%7D%7B2w%7D~~%3D~~%5Cstackrel%7B%5Ctextit%7Bcosts%7D%7D%7B33%7D%20%5Cend%7Bcases%7D%5Cqquad%20%5Cimpliedby%20%5Ctextit%7Blet%27s%20use%20elimination%7D%20%5C%5C%5C%5C%5B-0.35em%5D%20~%5Cdotfill%5C%5C%5C%5C%20%5Cbegin%7Barray%7D%7Bllccccccl%7D%203c%2B5w%3D15%26%5Ctimes%20%28-4%29%5Cimplies%20%26-12c%26%2B%26-20w%26%3D%26-60%5C%5C%2012c%2B2w%3D33%26%2612c%26%2B%262w%26%3D%2633%5C%5C%20%5Ccline%7B3-7%7D%5C%5C%20%26%260%26%26-18w%26%3D%26-27%20%5Cend%7Barray%7D)
Answer:
-16
Step-by-step explanation:
(x, y ) → (- 1, 3 )
The solution to the system of equations is the point of intersection of the 2 lines
From the graph, that is (x, y ) → ( - 1, 3 )
We can confirm by solving algebraically
Since both equations express y in terms of x we can equate the right sides
- x + 2 = - 6x - 3 ( add 6x to both sides )
5x + 2 = - 3 ( subtract 2 from both sides )
5x = - 5 ( divide both sides by 5 )
x = - 1
substitute x = - 1 into either of the 2 equations for y-coordinate
y = - x + 2 = 1 + 2 = 3
solution is (x, y ) → (- 1, 3 )
