The percent of tax returns filed electronically in 2001 was 30.7%. In 2013, the figure was 82.9%. 

(a) Use the information given for the years 2001 and 2013, letting x = 0 represent 2001, x = 12 represent 2013, and y represent the percent of returns filed electronically, to find a linear equation that models the data. Write the equation in slope-intercept form. Interpret the slope of the graph of this equation.

(b) Use the equation from part (a) to approximate the percent of tax returns that were filed electronically in 2009.