Math game with 'hard' and easy questions
A few notes touching upon encapsulation and responsibilities:

    def __init__(self):

        print("Welcome to the Official Math Game of SkillsUSA!\nYou will have at least five relatively simple questions,\nand up to ten difficult ones.\nGood luck!")
        time.sleep(5)
        x = 3
        while x != 0:
            print("Starting in ",x,"...")
            time.sleep(1)
            x -= 1


the initialization method of a class should be responsible to get the object into a workable state. It's supposed to initialize any required fields and then stop there.

This one here doesn't. Whenever some code creates a "new instance" of Math_game you'll get this welcome message, your thread will be locked up for 8 seconds, all this is stuff you don't want to have in your initializer. Only after that you get to the actually interesting stuff, namely initializing your fields.

Additionally this method is missing a docstring (that seems to be rather unconventional on __init__ methods, thanks to Gareth Rees) and instead has some non-parsable comments, which are suited to explain the code to python beginners (like I am one :D). You might prefer to add the docstring on class-level as suggested by Gareth.

That being said, your "cheesy intro" should be a separate method, taking a few parameters.



Next thing is: whenever a module gets imported in python, code in there is executed. This includes your current code. You definitely shouldn't do that. 

The simple and idiomatic fix for that is:

if __name__ == '__main__':


For more information on this construct, read up at stackoverflow



Overall your class could use more "API documentation". As of now if I wanted to use this from somewhere else, as a minigame or something, I'd have to jump through some hoops (with the problematic __init__ only being the first). This includes the less convenient name prob. This method takes two arguments and if I didn't have the source code, I'd have no clue what they were.

The first step to fixing this is getting a proper docstring in there. The next thing is to extract some responsibilities to clarify your design.

You should not return the solution when generating the problem. Instead you should store it somewhere in the class instead, so it can be checked properly with isCorrect.



While we're there: Your naming is sometimes a little off. You're violating the official conventions in a few places isCorrect being one of them. Methods, as well as variables and fields are supposed to be named in snake_case, Classes are supposed to be named in CapWords (without underscores)...

There's also tools that check the PEP-8 conventions for you, one of them being the IDE pycharm. Make use of these tools to simplify your life when coding ;)