The school cafeteria offered a choice of pizza or nachos to sixth-graders students. Seventy-seven students chose pizza. This represented 35% of the sixth grade class. How many students are in the sixth grade

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?