Find the ratio a:b, if it is given that a/3 = b/4

What is the value of y? round to the nearest tenth

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?

The percent of change from 12 to 15