Need help please help me will give branliest

Find the area of an equilateral triangle with a side of 6 inches

With number 11 ( show how you got the answer)

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?