Given two points m and n on the coordinate plane, find the slope of mn and state the slope of the line perpendicular to mn

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?

Liz had 140 pens and inna had 100 pens. after inna gave liz some pens, liz had 3 times as many pens as inna. how many pens did inna give liz?

Solve the following pair of equations for x and y: ax/b_ by /a= a +b; ax - by = 2ab