Question

josiah is taking his friends to the movies each ticket cost $10, and popcorn is $5 a bag. there is a 3$ service fee for the entire purchase

Answer 1

He can buy 6 bags of popcorn MAX!! 
Hope this helps!!

Answer 2

X = total amount paid
y = number of tickets
z = number of bags

your equation:
x = 10y + 5z + 3

hope this helps