This is worth 22 points if you show work you will get the Brainliest answer if your unable to show work type it for your explanation plz ( no links )

Express the following as a function of a single angle. cos(60) cos(-20) - sin(60) sin(-20)

What does the sign of the slope tell you about a line?

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?