How do I override a balance?

Question

Ok so I have a renting terminal program, but I don't know how to update my balance. I start off with $100 and when a movie is rented it subtracts however much it was, but when I rent another movie it just gets subtracted starting from $100 again and not from however much is left. How do I fix this? Also assuming every movie has only 1 in stock how do I prevent a movie from being rented twice? Thank you.

Answer 1

it says I dont have internet connection

Answer 2

ok I called it "rental terminal need help"

Answer 3

did you see it? please help me

Answer 4

share ur code, Jesse

Answer 5

Jesse copy this codes in ur code section where u run them, and mk it public , we can better check it out there,