What's thee error and the solution

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

Carl's candies has determined that a candy bar measuring 3 inches long has a z-score of +1 and a candy bar measuring 3.75 inches long has a z-score of +2. what is the standard deviation of the length of candy bars produced at carl's candies?

Find the value of x to the nearest tenth.