(4) The diagram shows a square with areas \( A, B, C \) and \( D \).
The ratio of Area \( A \) to Area \( B \) is \( 2: 5 \).
The ratio of Area \( B \) to Area \( C \) is \( 2: 1 \).
The area of \( D \) is \( 45 \mathrm{~cm}^{2} \).
(a) Find the ratio of Area \( A \) to Area B to Area C.
(b) Find the area of the square.