Need help with alg2 math

Amber had 1/6 of a pie left after the bake sale. rihanna had 3/8 of a pie left. what fraction of a pie did they have altogether?

Barbara's piano instructors house is 7 1/8 miles from her house. after biking for 1 3/4 miles she stops to rest how much longer does she need to bike to reach her instructor's house

Determine the mean and variance of the random variable with the following probability mass function. f(x)=( 729divided by 91) (1 divided by 9) superscript x baseline comma x equals 1,2,3 round your answers to three decimal places (e.g. 98.765).