Help me figure out this

To decrease an amount by 16% what single multiplier would you use

Eden has a part time job. she is paid ? 7.20 an hour the week she worked 18 and a half hours how much is she paid

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?