How do you evaluate #g(10)# given #g(x)=-3x+1#?

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?

Find the value of x for which the lines are parallel.

Does anyone know how to do geometryme with this problem