Here's the answer:
“どこで買えますか?”
(doko de kae-masuka)
Watch a real native speaker say it:
Here's how it sounds in a textbook:
Fun fact: the hundreds of thousands of people learning Japanese with Memrise get this phrase correct 94.51% of the time!
(doko de kae-masuka)
Fun fact: the hundreds of thousands of people learning Japanese with Memrise get this phrase correct 94.51% of the time!