Please help me been stuck on this for awhile now

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).

Micheal is 4 times as old as brandon and is also 27 years older than brandon. how old is micheal

One positive integer is 2 less than another. the product of the two integers is 24. what are the integers?