This year I'll have 180 hours free during which I can play video games or watch movies. Each movie lasts 2 hours, and I'll be able to play each video game for 20 hours. I have $600; each movie costs $10, and each game costs $40. (a.) If I make 3 new friends every time I get a new video game but still make 1 friend every time I watch a movie, how many movies should I watch this year to maximize the number of new friends I make?

(b.) If I instead make 5 friends every time I get a new video game and 1 friend every time I watch a movie, how many movies should I watch this year to maximize the number of new friends I make?

(c.) Suppose I want to make as many new friends as possible. What is the smallest whole number of new friends each new video must give me in order for it to make sense for me to buy only video games this year?