robots.txt is prefix matching, so a rule like Disallow: /?b=9 will block all URLs that start /?b=9. Your URLs start /shopp... so they are not blocked.
However, you can use a * (wildcard - 0 or more instances of any character) to represent the first part of the URL. This is an addition to the "standard", but the main search engine bots support it:
Disallow /*/?b=9
The above should block /shopping/books/?b=9 and /<anything>/?b=9.