The number of text messages, y (in billions), sent in the United States since 2005 can be modeled using the equation y=18.8(3)x ,where x is the number of years after 2005. In what year were there approximately 4.6 trillion text messages sent?

In the figure below, ∠dec ≅ ∠dce, ∠b ≅ ∠f, and segment df is congruent to segment bd. point c is the point of intersection between segment ag and segment bd, while point e is the point of intersection between segment ag and segment df. the figure shows a polygon comprised of three triangles, abc, dec, and gfe. prove δabc ≅ δgfe.