the coordinates for a rhombus are given as (2a,0),(0,2b),(-2a,0) and (0,-2b) write a plan to prove that the midpoints of the sides of a rhombus determine a rectangle using coordinate geometry be sure to include the formulas

Answer asap and if you do you will get brainliest. catherine buys a gallon of ice cream from the store. after taking it home, she eats a fifth of a gallon of ice cream. her sister eats some of the ice cream as well. if two-thirds of the original amount of ice cream is left, then what fraction of a gallon of ice cream did her sister eat?