Shanices school is selling Tickets to the annual talent show. On the first day of ticket sales the school sold 5 adult tickets and 8 child tickets for a total of $102. The school took in $39 on the second day by selling 2 adult tickets and 3 child tickets. Find the price of an adult ticket.

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.