PLEASE HELP 3/4x - 7 = 3 (1/6x +1)

Solve the linear equation and determine whether it’s one solution or infinite solution or no solution

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).

Molly shared a spool of ribbon with 12 people. each person received 3 feet of ribbon. which equation can she use to find r, the number of feet of ribbon that her spool originally had?

Ineed with question three. i don't understand how i'm supposed to achieve 3 marks.