What is the solution set for the open sentence with the given replacement set? 15−x=9, {5, 6, 7, 8}
please help me

Which expression is not a polynomial?

Monitors manufactured by tsi electronics have life spans that have a normal distribution with a standard deviation of 1800 hours and a mean life span of 20,000 hours. if a monitor is selected at random, find the probability that the life span of the monitor will be more than 17,659 hours. round your answer to four decimal places.

1.based of the diagrams what is the the value of x? 2.how would you verify your answer for x