The difference between 13 and a number k in algebraic expression?

An arc subtends a central angle measuring 7pi/4 radians what fraction of the circumference is this arc?

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.

Me find the value of x each figure.