Why did paolo add 3(x + 2) to itself and subtract 8 page 151-152

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

Polynomial that can be factored as (3x-4)(3x+4)

How many triangles can be drawn with side lengths 4 centimeters, 4.5 centimeters, and 9 centimeters? explain