If one angle of a quadrilateral measures 120^∘ and its remaining three angles are equal in measure to one another, then the measure of each of these three remaining angles is equal to ?

Correct option is A

​Given:

One angle: 120^∘

Remaining three angles are equal.

Formula Used:

Sum of angles in a quadrilateral:

Sum = 360^∘

Solution:

Remaining angle sum: 360^∘ − 120^∘ = 240^∘

Each equal angle: $$\frac{240^\circ}{3} = 80^\circ$$​