Please help! i have a certain amount of time. i'll give brainliest

Acircle has a diameter will endpoints of (-2,8) and (6, 4). what is the center of the circle

Pls! does anybody know a shortcut for answering these types of questions in the future?

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?