A. X is the number of years after 2000
2006-200 = 6 years.
Replace x with 6 and solve:
105(6)^2 + 680(6) + 4296 = 12,156
Answer for part a: 12,156
Answer for part B.
There was just over 12,000 in 6 years , to get to 21,500 would be a little over 9,000 more 9/12 = 0.75
6 years x .75 = 4.5 years
6 + 4.5 = 10.5 years round to 10 years for estimating purposes
Answer for part b: about 10 years