The product of 16 and 4 less than a number is 208. find the number algebraically

Find the cosine function that is represented in the graph.

While on a train trip, marsha noticed that there were 35 people in her train car. after the next stop, there were only 21 people in her car. if p represents the percent decrease in the number of people in marsha's train car, what is p?

Given the following point on the unit circle, find the angle, to the nearest  tenth of a degree, of the terminal side through that point, 0≤θ< 360. p=([tex]\frac{ \sqrt{10} }{4} [/tex]