Doughnuts are being sold in bags and cartons a bag holds 4 doughnuts and a carton holds 10 doughnuts tom buys b bags of doughnuts and c cartons of doughnuts he buys a total of t doughnuts write down a formula for t in terms of b and c

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?