Definition: Given the Question and Answer pair, detect whether the answer is acceptable or not. Denote acceptable answer as "yes", otherwise denote as "no". An acceptable answer is consistent with the context in question, detailed, long, and uses general knowledge of English. Answers that are not definite and suggest a variety of options are not acceptable answers.
Input: Question: Imagine you're in a bar and order a pint of beer, which is 3.20. You only have a 10 note but want to tip the barkeeper. As you can't use 'keep the change' for obvious reasons, what do you say to tip the barkeeper 80 pence, making the total price 4? 
Answer: Please don't! In those sensible countries whose worker economy does not rely predominantly upon the random generosity of strangers (which never made any sense to me at all, but there we go), the cost of item X is C(X) and C(X) is what the till comes up with when you hit the button for X. It's insanely awkward to be given D but instructed to charge E, then to try to get the till to accept E as payment for X instead of C(X) whilst rendering D-E in change. And then all you're going to do is put D-C(X) in a little jar anyway. At best it takes a moment to figure out; at worst it ruins the end-of-day take calculations when a take of T is no longer equal to C(X)*N(X) across all items X. It could even throw off a stock check if executed sufficiently poorly by front-line staff. Even worse, bosses could start to suspect misconduct from staff fiddling the money they've been given by customers, and it would be difficult to prove your innocence from video-only surveillance. Just make your transaction like a normal person, paying D for X and getting D-C(X) as change in return then say "here, keep this; I have enough shrapnel as it is!", make an audible awkward chuckle, smile, and walk away.

no