I need help to understand this type of math, ive tried to use the app to search for answers and hope they would give me a explanation but im still unable to pass. so please explain how I can understand this.​

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

The physical fitness of an athlete is often measured by how much oxygen the athlete takes in (which is recorded in milliliters per kilogram, ml/kg). the mean maximum oxygen uptake for elite athletes has been found to be 60 with a standard deviation of 7.2. assume that the distribution is approximately normal.

Use the coordinates of the labeled point to find a point-slope equation of the line (3 -5)