The sum The first six terms of a geometric series is 15,624 and the common ratio is 5 what is the first term of the series

How do you solving the solution of each system using elimination?

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.

When 142 is added to a number the result is 64 more then 3 times the number. option 35 37 39 41