Find the missing length indicated. Leave your answer in simplest radical form.

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

Tom had a total of $220 and he spent $35 on a basketball ticket . what percent of his money did he have left?

Ateacher brought a pack of 17 batteries . each calculator uses 3 batteries . how many calculator can the teacher fill with batteries