Evaluate the following expression using the values given: find 3x2 − y3 − y3 − z if x = 3, y = −2, and z = −5. numerical answers expected!

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?