Please help ASAP: A contractor records the areas, in square feet, of several houses in a neighborhood to determine data about the neighborhood. Which formula should be used to calculate the standard deviation?

Aband wants to create a cd of their last concert. to creat the cds, the cost will be $350 advertisement fee plus $3 per cd.write an inequality that represents how many cds they can buy with a maximum of $1225.solve the inequality