6. slopes of perpendicular lines are negative reciprocals of each other. Therefore if CD is

, the slope of AB will be -

7. Note that the y intercept of the line is (0,8). Also note that another point on the line is (3,4). Now use these two points to find the slope

Moving from point (0,8) to (3,4), we go down 4 and to the right 3. Therefore, the slope is -

. At this point, we can just substitute into slope intercept form of a line: y = mx + b or

8. First find the slope of the line containing the points (-2,-3) and (2,5): The slope is

Now substitute that slope and the point (-4,5) into point slope form of the a line. You get:
y - 5 = 2(x + 4)