Could you please explain the answers to both questions? Thanks!

3382-299=3383- ? fill in the blank?

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.

Solve 13 + w/7= -18 (w/7 is a fraction)