5. In a plaza, the monthly rental of a shop of A m² on the nth floor is $R. It is given that R varies directly
as A and inversely as n. Charles and Diana are going to rent shop C on the 4th floor and shop D on the
3rd floor of the plaza respectively. The monthly rentals of shops C and D are in the ratio of 3:5.

(a) Find the ratio of the areas of shops C and D.

(b) Charles finally decides to rent shop E on the 2nd floor instead. The area of shop E is 22% smaller
than that of shop C.

(i) Find the percentage change in the monthly rental paid by Charles.

(ii) Charles claims that the monthly rental paid by him now is still less than that paid by Diana.
Do you agree? Explain your answer.