A quick (not the "right way to do it", and not recommended) answer would be to replace that line with:
.', answer='.$vars
Please note that probably removes ALL of the checking that the system does to try to make user inputted data "SAFE" to be put into the database. So this would be a security risk.
The correct way would be to go take a look at the db_input() function and the Format:() function and make copies with different names specifically to use with fields that you want to allow html with. You would then use the new functions here instead of the old ones (and would be able to then use them other places as well).
This article at Stackoverflow might help:
http://stackoverflow.com/questions/129677/whats-the-best-method-for-sanitizing-user-input-with-php(http://stackoverflow.com/questions/129677/whats-the-best-method-for-sanitizing-user-input-with-php)