There are lots of exercises in the Gardner book and of course tons in any calculus textbook. Most calc texts will also have student solution manuals to go along with the exercises, but they may or may not be pricier, you just have to check.
But there are also quite a few books like this out there: https://www.amazon.com/Calculus-Practice-Problems-Dummies-Online/dp/111849671X
There is a youtuber called PatrickJMT. He does a lot of Calculus problems on his vhannel and even wrote a book of problems. Here is the link. Good luck!
if you don't mind spending $20 this book is good
Calculus: 1,001 Practice Problems For Dummies
https://www.amazon.com/gp/product/111849671X
its made by this guy
http://patrickjmt.com/
and he's pretty good
Depends on what you want to do, but Linear Algebra would be a good bet because it shows up damned near everywhere. As for math problems, try googling for "1001 _______ Problems" workbooks, for example this one is relatively inexpensive (and also written by another math youtuber!)