Answer:
B
Explanation:
Matches all the points on the graph
The area of D is given by:

The average value of f over D is given by:
Well, if you just divide 4000 by 50, you can see that the answer will come out as:
<em><u>80
</u></em>~TO check: 80 multiplied by 50 would come out to the answer of 4,000.
<em>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~</em><em><u>
</u>Hope this helped! :D</em>
Angle 1 is a right angle =90 °
so 5x-85=90
5x=90+85
5x=175
x=35