In a circle, chord MN subtends two inscribed angles at points P and Q on the same side of MN.
(i) Given ∠MPN=(4x+15)∘ and ∠MQN=(7x−9)∘, determine the value of x and hence the measure of each angle.
(ii) Using your result from part (i), find the size of the central angle ∠MON, where O is the centre of the circle.