12. Use the slope formula to determine the slope of a line that passes through the points (4, 9) and (-8,-6).

13. Use the slope formula to determine the slope of the line that passes through the points (-5, -3) and (9, -10).

14. Explain how to find the slope of a line from a graph.

15. Explain how to find the slope of a line when given two points on the line.​