What is the slope of the line with the equation 3x + y = 15?

What number should be added to both sides of the equation to complete this square? x^2-10x=7

Read the situations in the table below. then drag a graph and equation to represent each situation. indicate whether each of the relationships is proportional or non-proportional. edit : i got the right answer its attached

Can you me find the missing length. i attached an image.