In a quadrilateral ABCD inscribed in a circle, the measures of two opposite angles are given by ∠A=3x+15∘ and ∠C=5x−25∘.
(i) Find the value of x.
(ii) Hence calculate the numerical values of ∠A and ∠C.
(iii) If ∠B:∠D=4:5, determine the measures of ∠B and ∠D.