Explain how to solve for x? 40^x=15

Place the following steps in order to complete the square and solve the quadratic equation,

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.

Do, h = (7, 9) (14, 18) the scale factor is