In a cyclic quadrilateral, the sum of the opposite angles is 180 degrees. If ∠BAC is 70 degrees and AB is equal to BC, triangle ABC is isosceles and thus ∠ABC is also 70 degrees. The sum of the two opposite angles of quadrilateral ABCD is ∠ABC + ∠ADC = 180 degrees. By substituting the known angle ⦟ABC = 70 degrees, we have ∠ADC = 180 - 70 = 110 degrees.

Option 1 suggests that ∠ADC is 40 degrees, but this would imply that the sum of the opposite angles is less than 180 degrees, which is not possible in a cyclic quadrilateral.

Option 2 says that ∠ADC is 80 degrees, however, this is not possible as our calculation shows that ∠ADC should be 110 degrees.

Option 3 suggests ∠ADC = 110 degrees. This is incorrect, as it incorrectly assumes that ∠ABC (70 degrees) and ∠ADC equal each other, but this goes against the idea that the two opposite angles in a cyclic quadrilateral should sum to 180 degrees.

Option 4 presents that ∠ADC = 140 degrees. The mistake