The total bill for an exterminator was $385. She charges $35 to spray each room. How many rooms were sprayed?

You are a clerk at convenience store. a customer owes 11.69 for a bag of potatoes chips. she gives you a five dollar bill. how much change should the customer receive?

The fence around a quadrilateral-shaped pasture is 3a^2+15a+9 long. three sides of the fence have the following lengths: 5a, 10a-2, a^2-7. what is the length of the fourth side of the fence?

The standard deviation for a set of data is 5.5. the mean is 265. what is the margin of error?