Solve each problem. Give equations in slope-intercept form.

Total sales of smartphones in the United States (in billions of dollars) are shown in the graph, where the year 2013 corresponds to x = 0.

(a) Use the ordered pairs from the graph to write an equation that models the data. (Round the slope to the nearest tenth.) Interpret the slope in the context of this problem.(b) Use the equation from part (a) to approximate smartphone sales in the United States in 2014, the year data was unavailable.

Sales (in billions of dollars) Smartphone Sales y 55 50 45 40 0 (3, 54.5) (0, 43.0) 1* 2 3 Year