Answer:
They encircle the planet
times.
Step-by-step explanation:
Consider the provided information.
We have 2.5 mole of dust particles and the Avogadro's number is 
Thus, the number of dust particles is:

Diameter of a dust particles is 10μm and the circumference of earth is 40,076 km.
Convert the measurement in meters.
Diameter: 
If we line up the particles the distance they could cover is:

Circumference in meters:

Therefore,

Hence, they encircle the planet
times.
Answer:B
Step-by-step explanation:
The answer to this, maybe.., is 180
Answer:
the answer is B) 12a+6b
Step-by-step explanation:
3+9=12 so 3a+9a=12a,
7-1=6 so 7b-(1)b=6b
9/8 divided by 3/8 is 3 (because of the same denominator look at the first number)
3/5 divided by 2/3 is 0.9 hope this helps