Solve the equation by completing the square

What is the slope of the line shown below?

Empty box + box + empty box fill in the box is equal to 30 how

Lindsay used two points, (x, y; ) and (+2.82), to find the equation of the line, y = mx + b, that passes through the points. y2-y, first, she used the definition of slope and determined that the value of mis x, - . given this information, which expression must represent the value of b?