A committee of 7 has to be formed from 9 boys and 4 girls.In how many ways can this be done when the committee consists of A committee having at least 3 girls will consists of (a) 3 girls 4 boys (b) 4 girls 3 boys

Question

$\begin{array}{1 1}(A)\;504\\(B)\;508\\(C)\;588\\(D)\;590\end{array} $