Answer:
See Below
Explanation:
The equation estimating the number of cellphones in the country is:

Where x = 0 corresponds to year 2000
thus,
x = 1 is year 2001
x = 2 is year 2002
x = 3 is year 2003
and so on...
We want approx. number of cellphones in the country in 2003. This corresponds to x = 3. So substituting in the equation we get:

So, approximately there were 167.03 million cellphones in the country in 2003