Which expression represents the difference between 18 and an unknown number a. 18 - n b. 18 + n c. 18 divided by n d. 18 • n

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?

Triangle xyz has vertices x(1,3), y(0,0)

[10 points, algebra 2-simplifying complex fractions]according to my answer key the restrictions are -1 and 4. but why not positive 1?