(24·z^3)^2/(27·12·z) = (2^3·3·z^3)^2/(3^3·2^2·3·z) = (2^6·3^2·z^6)/(3^3·2^2·3·z) = 2^4·3^(-2)·z^5
a = 4 ; b = -2 ; c = 5