Can some one help me please!?!

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

At the beginning of the year, adrian's savings account balance was \$28$28. each week, he deposits another \$15$15 into that account, and he doesn't spend any of his savings. is his savings account balance proportional to the number of weeks since the start of the year?

Which rotation about its center will carry a regular hexagon onto itself