What shape is a rectangle but is not a square

Determine whether the set of whole numbers is closed under addition. explain why the set is or is not closed. give an example.

Given abcd ac=38 and ae=3x+4 find the value of x

Select the margin of error that corresponds to the sample mean that corresponds to each population: a population mean of 360, a standard deviation of 4, and a margin of error of 2.5%