It's 42, here's a quick trick to do this, so we know there's 7 movies, and to find the combination we know we can't choose 2 of the same movie, so to make this part easier , in your head take one movie from the stack out of the stack now there's 6 movies. It's now just the "plug and play" step , (7)*(6)=(42)
I'm sorry If this is to long of an explanation, but I hope that this helps you understand on how to do this problem. Have a nice day :)
The answer to your question is n=0 or n=1/10
Use a ruler. I can't see the picture.
