Work out the equation of the line which has a gradient of 1/2 and passes through the point (4 -2)

How to do this , and can some one explain

State if the two triangles are congruent. if they are, state how you know?

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.