Quadrilateral OPQR is inscribed in circle N, as shown below. Which of the following could be used to calculate the measure of ∠QRO? m∠QPO + (x + 16)° + (6x − 4)° = 360° m∠QPO = (x + 16)° + (6x − 4)° m∠QPO + (2x + 16)° = 180° m∠QPO = (6x − 4)° + (2x + 16)°