At an office supply store emilio bought 3 notebooks and 5 pens for $13.75 if a notebook costs $1.25 more than a pen how does one notebook cost?

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?