The sales of a company (in million dollars) for each year are shown

The sales of a company (in million dollars) for each year are shown in the table below.

X(year)
2005
2006
2007
2008
2009

Y(sales)
12
19
29
37
45

a) Find the least square regression line y = ax + b.
b) Use the least squares regression line as a model to estimate the sales of the company in 2012.