You haven't posted the answer choices, but I think I've run across this question before and remember the answer. The answer should be whichever letter says as follows: "Smoking damages cilia in the trachea and more particles enter the lungs. Hope this helps!~
x is -7
Step-by-step explanation:
21 ÷ -3 = -7
a negative times a negative equals a positive
Answer: The required percentage is 75% of print area filled with advertisement.
Step-by-step explanation:
Since we have given that
Part of the print area of the newspaper carried new = 
Rest was filled with advertisements = 
So, Percentage of the print area was filled with advertisement is given by

Hence, the required percentage is 75% of print area filled with advertisement.
Answer:
Step-by-step explanation:
There are an estimated 29,819 fire departments in the US Of these, 2,785 ... provided EMS service and advanced life support, and 11,559 (39%) of departments ... The authors would also like to thank the members of the NFPA staff who ... Figure 2 Number of Volunteer Firefighters and Rate per 1,000 Population. 4.
i hope this fact helps some
Simplified: 
Restrictions: x CANNOT be 0 because then the denominator would become 0 and would not be possible