Which of the following is a linear function?

Suppose a least-squares regression line is given by modifyingabove y with caret equals 4.302 x minus 3.293. what is the mean value of the response variable if xequals20?

An advertising firm has an old computer that can prepare a whole mailing in 6 hours. with the of newer model the job is complete in 2 hours. how long would it take the newer model to do the job alone?

Arace is 10 kilometers long. markers will be placed at the beginning and end of the race course and at each 500 meter mark. how many markers are needed to mark the course for the race?