Literally 50 points for whoever can answer this

What is the quadric regression equation that fits these data

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?

How do you determine whether a relationship represented as as graph is linear or nonlinear