Answer:
21
Step-by-step explanation:

Tan 40 = h / 20 where h = height of the pole.
h = 20 tan 40 = 16.78 feet
The question is asking for mass/unit of volume.
Therefore the density of the material would be 6400kg/0.8m^3. You then want to change the bottom into a 1 by multiplying the top and bottom both by 10/8. You now have 8000kg/m^3, which is the solution.
C= (3, -5) aND D= (6, 0)
y-y1 = m (x -x1).
i.e. if x1, y1 = 3, -5 and x2, y2 = 6,0 then#
y- (-5) = m(x - 3), so all we are missing is the slope:
Y2 -y1
--------------- = m (the slope)
x2 -x1
0-(-5)
------- = 0+5 /3 = 5/3
6 - 3
therefore equation of line is y+5 = 5/3 (x - 3)