Translation:He sells that book at the maximum price.
"Price" in a translation is always a specific amount. Things are sold at "a price" or at "the ...... price." They don't have "price" they have "a price." At the very least, it is not wrong to use an article in the English translation of this sentence.
To add to that, it should not be "with maximum price" but rather "at the maximum price".
The English translation isn't one you'd find in actual usage of the language.
It's better to say: "He is selling that book for the maximum price." More idiomatically, you'd really have to say "He is selling that book at the highest possible price."
Why can't I report the English as very awkward? Has that been recognized and we are just waiting for a fix?
This is the third damn sentence where the translation has changed to what was previously taught without any explanation. Với has new translation, the old with fits but still...And drop down hints as usual are questionable and frequently do not include new definitions.