Can someone help me with these problems?

To complete your spring schedule, you must add calculus and physics. at 9: 30, there are three calculus sections and two physics sections; while at 11: 30, there are two calculus sections and three physics sections. how many ways can you complete your schedule if your only open periods are 9: 30 and 11: 30?

What’s the domain of this function? fast

If the value of cos330°is√3/2 then find cos 165°.