How to find volume of triangular prism

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.

What is r i 4.5+10r=-6.5 with work pls

Astudent showed the steps below while solving the inequality |x-4|< 1 by graphing.