Help me please 12x-30​

Which equation represents a direct linear variationa. y=x2b. y=2/5xc. y=1/xd. y=x+3

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?

What are the solutions of the following system? y=-2x^2 y=x-2