Mary paid #13.60 on a hamster toy, and a cage cost her $14.90 with 2 $20 bills. she also found a dollar bill on the ground. how much change did she receive?

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?