Which relation is a function?

The suare root of 9x plus 7 plus the square rot of 2x equall to 7

Select the margin of error that corresponds to the sample mean that corresponds to each population: a population mean of 25, a standard deviation of 2.5, and margin of error of 5%

Write an inequality for this description. - one fourth of the opposite of the difference of five and a number is less than twenty.