How can you know if this equation is true? 13+15=28=14

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).

Complete the solution of the equation. find the value of y when x equals to 1 9x-5y=29

Rewrite so the subject can be y in the formula d=m-y/y+n