PLEASE HELP!! adding and subtracting rational expressions
how did they get 9?? please help i don't understand

Let the mean of the population be 38 instances of from 6" - 9" hatchings per nest, and let the standard deviation of the mean be 3. what sample mean would have a confidence level of 95% or a 2.5% margin of error?

X+y=-4 x-y=2 use elimination with adding and subtraction

Factor the polynomial expression x6 – x3 – 20