Quadrilateral opqr is inscribed in circle n, as shown below. which of the following could be used to calculate the measure of ∠rop? circle n is shown with a quadrilateral opqr inscribed inside it. angle o is labeled x plus 16. angle p is not labeled. angle q is labeled 6x minus 4. angle r is labeled 2x plus 16. (6x − 4)° + (2x + 16)° = 360° (x + 16)° + (6x − 4)° = 360° (6x − 4)° + (2x + 16)° = 180° (x + 16)° + (6x − 4)° = 180° (i can provide a picture, if needed.