Wait you say the beers=2 in your calculation (in the matrix) then use a 1 instead of a 2.... Which means the correct answer is 25 right? 5+(2x10)=25

Then in the 2nd one you replace 15 with 11 in a similar fashion... So the answer would be
2+3+(3×15)=52.. right?

Am I missing something? I just used a matrix from linear algebra originally to solve for the variables... I could be wrong. I will update after plugging it into a calculator.

Update: I was wrong, gotta pay attention to the details.