Can anyone figure this out and explain?

According to the normal model, what percent of receivers would you expect to gain fewer yards than 2 standard deviations below the mean number of yards

1/2+1/6-3/4 simplify the given expression leaving the answer in improper fraction form.

Ken leaves work 20 minutes late. he decides to make up time by taking the toll road instead of side streets. he can travel three times faster by taking the toll road. create an equation to represent his total travel time, including wait time, where x is the number of minutes the drive was expected to take