Check the picture below.
the triangle is an 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.
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 cuts it in (x/2)°.
now, we know ∡ADB is 110°, therefore its supplementary angle, in green, is 70°.
recall that the sum of all interior angles in a triangle is 180°, thus