HELP ASAPPP FOR EXAMS

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?

What are “like terms”? why can we only add like terms?

Write numerical coefficient of y² in the expression 2x² - 15xy – 7y²