8 True or False: The substitution method is a method of solving systems of equations by adding equations together in such a way that the variables are set aside, one by one.

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Solve the given system of equations. 2y= -x+9 , 3x-6= -15

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.