MathNet 2020 — Math Olympiad Vault — Part 05 Question 34

In the figure, $\angle ABC=100^\circ$, $\angle FAC=3\angle ECB$, and $\angle GCA=3\angle DAB$. Find the acute angle at the intersection of the internal bisectors of angles $D$ and $E$ in triangles $ADB$ and $CEB$, respectively.