Okay, here we have this:
Considering the provided information we obtain the following:
Meatballs remaining = Total meatballs - Meatballs that the dog ate
Meatballs remaining = 160 - (160*3/20)
Meatballs remaining = 160 - (480/20)
Meatballs remaining = 160 - 24
Meatballs remaining = 136
Finally we obtain that Jason has 136 meatballs left.