How do you do this question? and what does the bar lines mean, is it absolute value?

What is the slope of the line that contains the points (4,8) and (9,8)? what type of line is it?

Elena and her husband marc both drive to work. elena's car has a current mileage (total distance driven) of 15,000 and she drives 23,000 miles more each year. marc's car has a current mileage of 46,000 and he drives 9,000 miles more each year. will the mileages for the two cars ever be equal? explain.

What number should be added to the expression x^2+3x+ in order to create a perfect square trinomial? 3/2 3 9/4 9