I think it’s either C or D
First - 8
second - 4
third - 12
fourth - 9
So if you distribute 4 in the first parentheses, you get 12x+20y+8z.
Then you distribute 3 in the second parentheses. You'll get 3x-3z. That all equals 12x+20y+8z+3x-3z.
Now you have to start combining numbers with the same variable. Start with x. 12x+3x is 15x.
y has no other common variable, it's left alone.
8z-3z is 5z
All together now with the numbers in simpler form, the equation is 15x+20y+5z
Jenna's would be the right answer because when you distribute 5 in her answer you get 15x+20y+5z
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