The top question is already filled out (if you see an error in the top one can you let me know in the comments only please?) and what I need to answer is the bottom question, can any of you help me, please?

What is the lcm of 16 and 40 ? 24 and 40 ?

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?

Simplify the given expression leaving the answer in improper fraction form. 2/3+5/6