Write a sequence that has two arithmetic means between 9 and 24?

What is the 12th term of b(n)=-4-2(n-1)

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.

If abcde is reflected over the x-axis and then translated 3 units left, what are the new coordinates d?