Step-by-step explanation:
Very quick and effortless example of vertical angles in the attached image. When 2 straight lines intersect, the 2 angles opposite each other at that point are vertical angles, and they are always congruent.
I'd say it's the 3rd option:
"Vertical angles are a pair of non-adjacent angles formed by two intersecting lines."
but any of the first three could be technically true really. Adjacent angles are 2 angles that share a side, and vertical angles cannot share one.
Answer:
x = 70; the labeled angles are 110º and 70º.
Step-by-step explanation:
The full degrees will add up to 180º. There are 2x and +40.
Equation: 
Solve: 
Since x=70, 70+40 will equal to 110.
Therefore, "x = 70; the labeled angles are 110º and 70º." is correct.
Answer:
3
Step-by-step explanation:
The population after 8 min is 1200 sorry that's only one I got time for. I think it should right though.
Answer:

Step-by-step explanation:
Red blood cell: 
Grain of sand: 
The "how many times larger" part can be figured out by forming a ratio between the two diameters above:

Note that dividing the powers of ten corresponds to subtracting the denominator power from the numerator power of 10.