Please help me I'm bad with exponents.

Can someone me with my math problems i have a bunch. i will give brainliest and lots of pleeeaaasssee

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?

Which ordered pair is the best estimate for the solution of the system of equations? the graph of the system of equations : y = 3/2x +6 and y=1/4x - 2 , -3) .5, -3.5) , -4) , -3.5)