Do you add or multiply when you do area ​

Hannah works at the mall selling book bags. she sold 35 book bags in 5 hours. how many book bags did she sell per hour?

Thompson and thompson is a steel bolts manufacturing company. their current steel bolts have a mean diameter of 127 millimeters, and a variance of 36. if a random sample of 35 steel bolts is selected, what is the probability that the sample mean would differ from the population mean by greater than 0.5 millimeters? round your answer to four decimal places.

Use the elimination method to solve the systems of equations. choose the correct ordered pair. 7x+4y=39