We have a Winner!
š„ ...drum roll, please... š„
Congrats to @yura81 for winning the Amazon gift card! He also answered it correctly, even though that wasn't a requirement to win, with a mathematically meticulous method where he arrived at the answer* of 15.
The tricky part is noticing there is only one beer (not two) in the final equation, along with remembering that multiplication always happens before addition (unless you involved parentheses or weird stuff like that).
* Unless, of course, our own math skills are off. š
Thanks for playing! Stay tuned for another giveaway!