Enter the correct 4 digit code (no spaces)

Abby is preparing fruit punch for her party. she starts with a bowl filled with liquid that has 1/2 fruit juice and 1/2 sprite, but she decides it's too fruity. so she pours out 1/4 of the liquid, and then fills the bowl up again with sprite. what fraction of the punch is now sprite?

Write as a product: ac^2–ad+c^3–cd–bc^2+bd

What line represents the relationship between r and s