Answer:
$2
Explanation:
Lets say coffee's are x, and muffins are y. We would rewrite it as 2x + 4y = 18, and x + 3y = 11.
You put those equations over each other:
2x + 4y = 18
x + 3y = 11
Multiply the whole bottom equation by 2, because then you can cancel the x's out. It would look like this:
2x + 4y = 18
2x + 6y = 22
Subtract the equations from each other, to get -2y = -4. Then divide -2 from both sides to get 2.