<h2>Step-by-step explanation:<em><u> The triangle is isosceles, meaning it has two twin sides, that make two twin angles, namely AB = BC, and the angles at A and C are twins as well.
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</u></em></h2><h2><em><u>now, the AD segment, is an angle bisector, meaning it cuts the angle at A in two equal halves, so if say the angles are x° each, then the bisectors cut it in (x/2)°.
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</u></em></h2><h2><em><u>now, we know ∡ADB is 110°, therefore its supplementary angle, in green, is 70°.
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</u></em></h2><h2><em><u>recall that the sum of all interior angles in a triangle is 180°, thus Check out the photo below </u></em></h2>