Answer:
The answer would be C.
Step-by-step explanation:
Answer:
Your friend is incorrect because if you divide 21 by 7 you will get 3 if you add 7 to 3 you get 10 therefore your friend is incorrect.
Answer:
Part 4) 
Part 10) The angle of elevation is 
Part 11) The angle of depression is 
Part 12)
or 
Part 13)
or 
Step-by-step explanation:
Part 4) we have that

The angle theta lies in Quadrant II
so
The sine of angle theta is positive
Remember that

substitute the given value




Part 10)
Let
----> angle of elevation
we know that
----> opposite side angle theta divided by adjacent side angle theta

Part 11)
Let
----> angle of depression
we know that
----> opposite side angle theta divided by hypotenuse


Part 12) What is the exact value of arcsin(0.5)?
Remember that

therefore
-----> has two solutions
----> I Quadrant
or
----> II Quadrant
Part 13) What is the exact value of 
The sine is negative
so
The angle lies in Quadrant III or Quadrant IV
Remember that

therefore
----> has two solutions
----> IV Quadrant
or
----> III Quadrant
14 loaves per hour
15 hours will get 14×15 = 210loaves