Plzzz help me with this

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

Galen sold tickets of his church’s carnival for a total of $2,820. children’s tickets cost $3 each and adult tickets cost $5 each. the number of children’s tickets sold was 30 more than 3 times the number of adult tickets slod. how many children’s ticket and how many adult tickets did he sell?

What expression is equivalent to 42x-56y