Finding the sum of the measures of the interior angles of a convex nonagon

What is the volume of this container?

What is the slope of the line passing through the points (-5, 7) and (-3,5)?

Rose and andrew are financing $128,000 to purchase a condominium. they obtained a 15-year, fixed-rate loan with a rate of 5.05%. they have been given the option of purchasing up to four points to lower their rate to 4.81%. how much will the four points cost them?