<u>Answer:</u>
A,C and E are equal with 4 as their solution; F and B are equal with 0 as their solution. D is independent.
<u>Solution:</u>
A. 
Taking off the brackets we get,



Here x=4 --- (a)
B. 
Multiplying -4 inside we get,


Here x=0 --- (b)
C. 
Multiplying -2 inside we get,

Grouping the terms,


Here x=4 --- (c)
D. 


Here x=-6 --- (d)
E. 


Here x=4 --- (e)
F. 


Here x=0 --- (f)
So, from the above calculations we can conclude that (a), (c) and (e) are equal and (f) and (b) are equal but (d) is independent because it has a different solution.
Answer: a<c
| a | > | b |
Step-by-step explanation:

This result is actually true for any exterior angle. The exterior angle of a triangle is equal to the sum of the two remote angles, and above is a short proof of it.
Answer:

Step-by-step explanation:
![\displaystyle = \frac{x+7}{x^2+4x-21} \div \frac{x+5}{x^2+8x+15} \\\\Apply \ mid-term \ break\\\\= \frac{x+7}{x^2 +7x-3x-21} \div \frac{x+5}{x^2 +3x+5x+15} \\\\= \frac{x+7}{x(x+7)-3(x+7)} \div \frac{x+5}{x(x+3)+5(x+3)} \\\\Taking \ (x+3) \ and \ (x+7) \ common\\\\= \frac{x+7}{(x-3)(x+7)} \div \frac{x+5}{(x+3)(x+5)} \\\\= \frac{1}{x-3} \div \frac{1}{x+3} \\\\= \frac{1}{x-3} * (x+3)\\\\= \frac{x+3}{x-3} \\\\\rule[225]{225}{2}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%3D%20%5Cfrac%7Bx%2B7%7D%7Bx%5E2%2B4x-21%7D%20%5Cdiv%20%5Cfrac%7Bx%2B5%7D%7Bx%5E2%2B8x%2B15%7D%20%5C%5C%5C%5CApply%20%5C%20mid-term%20%5C%20break%5C%5C%5C%5C%3D%20%5Cfrac%7Bx%2B7%7D%7Bx%5E2%20%2B7x-3x-21%7D%20%5Cdiv%20%5Cfrac%7Bx%2B5%7D%7Bx%5E2%20%2B3x%2B5x%2B15%7D%20%5C%5C%5C%5C%3D%20%5Cfrac%7Bx%2B7%7D%7Bx%28x%2B7%29-3%28x%2B7%29%7D%20%5Cdiv%20%5Cfrac%7Bx%2B5%7D%7Bx%28x%2B3%29%2B5%28x%2B3%29%7D%20%5C%5C%5C%5CTaking%20%5C%20%28x%2B3%29%20%5C%20and%20%5C%20%28x%2B7%29%20%5C%20common%5C%5C%5C%5C%3D%20%5Cfrac%7Bx%2B7%7D%7B%28x-3%29%28x%2B7%29%7D%20%5Cdiv%20%5Cfrac%7Bx%2B5%7D%7B%28x%2B3%29%28x%2B5%29%7D%20%5C%5C%5C%5C%3D%20%5Cfrac%7B1%7D%7Bx-3%7D%20%5Cdiv%20%5Cfrac%7B1%7D%7Bx%2B3%7D%20%5C%5C%5C%5C%3D%20%5Cfrac%7B1%7D%7Bx-3%7D%20%2A%20%28x%2B3%29%5C%5C%5C%5C%3D%20%5Cfrac%7Bx%2B3%7D%7Bx-3%7D%20%5C%5C%5C%5C%5Crule%5B225%5D%7B225%7D%7B2%7D)
Hope this helped!
<h3>~AH1807</h3>