PLEASE SOLVE ASAP!
Ms Liu has $40 to buy water and popcorn at the movie theater. Popcorn costs $8 per bag and water costs 3$ per bottle. Write an algebraic expression that can be used to find the amount of money Ms Liu will have left if she buys any number of bags of popcorn (p), and any number of bottles of water (w).

Solve the blanks.
The algebraic expression _____ represents the amount of money Ms. Liu will have left if she buys any number of bags of popcorn and bottles of water.

Ms Liu will have $____ left if she buys 3 bags of popcorn and 4 bottles of water.