# A Neighboring Triangle

Geometry Level 3

Given that :

1. $\triangle ABC$ is an isosceles triangle, with $AB=AC$.
2. $\triangle ADC$ is an isosceles triangle, with $DA=DC$.
3. $\angle BAC = 100^\circ$
4. $\angle DAC = 20^\circ$

What is the measure of $\angle ABD$ in degree?

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