Which one is correct please help

Let w=23 . what is the value of w + 45 ?

Describe in detail how you would construct a 95% confidence interval for a set of 30 data points whose mean is 20 and population standard deviation is 3. be sure to show that you know the formula and how to plug into it. also, clearly state the margin of error.

Which expression is equivalent to7_/x^2 ÷ 5_/y^3? assume y# 0