Slope of line that passes through -9,8 and -21,10

How do you solving the solution of each system using elimination?

There is an entrance to the computer room at point e which lies on ab and is 5 feet from point a. plot point e on the coordinate plane. find the distance from the entrance at point e to the printer at point e

Which table represents a linear function? i'll give brainliest to first answer ^'^