Can someone help me with this question please

How to choose the sign of the radical in the denominator of the formula for the distance from a point to a line.

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 can you tell when x and y are not directly proportional?