Find the year when the user will turn 100
Your findYearWhenAge100() function has a print() statement, and returns nothing, so your __main__ doesn’t need to print the return value. 



A good habit is adding """docstrings"""  to your functions.  Eg)

def inputInfo():
    """Asks the user for name and age"""
    #... remainder of code




The userInput() function should do things like turning the userAge string into an int.  That should not be the responsibility of functions which need the age. 



Use pylint.  It will help you write more standardized code.  Things like a space is expected after a comma, not before.