PLZ HELP I DONT UNDERTSTAND I WOULD APPRICIATE IT

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).

F(x) = 1/x g(x)=x-4 can you evaluate (g*f)(0) ? why or why not?

Tiene pendiente -4 y pasa por el punto (-3,-2) encuentre la ecuación de la recta