The total amount paid by the U.S. government to individuals for Social Security retirement and disability insurance

Question:

The total amount paid by the U.S. government to individuals for Social Security retirement and disability insurance benefits during the period 2004–2013 can be approximated by the linear model y = 35.7x + 486, where x = 0 corresponds to 2004, x = 1 corresponds to 2005, and so on. The variable y is in billions of dollars. Based on this model, during what year did the amount paid by the government first exceed $800 billion? Round the answer to the nearest year. Compare the answer to the bar graph.

Social Security Retirement and Disability Insurance Benefits

1000 800 .... 600 400 200 **. '04 '05 '06 '07 '08 '09 '10 '11 '12 '13 Year Billions of dollars