Ineed with my math : ) (one is darker than the other)

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

Maurice has 54 fewer comic books than rebecca. they have 130 comic books together .how many comic books are in maurices collection ? how many comic books are in rebeccas collection

Find the perimeter of the triangle with vertices  d(3, 4),  e(8, 7), and  f(5, 9). do not round before calculating the perimeter. after calculating the perimeter, round your answer to the nearest tenth.