What type of solutions are there with these equations x+y=4 and y=2x-5?

Find the value of the cosine for angle a

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?

Erin bought christmas cards for $2 each to send to her family and friends. which variable is the dependent variable?