What is 25g^R4-268? Will mark brainliest

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?

When y’all answer can y’all explain too !

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?