Excuse my ignorance, I have absolutely no experience. How can I use a input variable (Such as user_age) in mutiple functions? Should I use a global variable. Appreciate any help

def main():
print('Hi! My name is Rover, what's your name?')
name = input('')
print('\\nPlease to meet you', name   '!')
print('\\nWell '   name   ' I'm from Mars! Where are you from?')
home = input('')
print('\\nWow! '   home   ' sounds so cool!')
print('\\nWhat's your age',name  '?')
calcMartinAge()
calcFare()

def usr_age():
user_age = int(input(''))
return user_age

def calcMartinAge():
MARTIAN_TIME = 1.88
Martian_age = str(int(usr_age() / MARTIAN_TIME))
print('\\nWOW! On Mars you'd only be '   Martian_age   '!')
return Martian_age

def calcFare(usr_age):
if usr_age \> 19 and usr_age \< 65:
print('\\nYa know your fare to Mars would only be $10,000!')
elif usr_age \< 12:
print('\\nYa know your fare to Mars would only be         $5,000!')
else:
print('\\nYa know your fare to Mars would only be $7,000!')

main()