A and B entered into a partnership with certain investments. At the end of 8 months A withdrew and collected back his money. A and B received profit in the ratio 5 : 9 at the end of the year. If B had invested Rs. 36,000, then how much (in Rs.) had A invested?

\[\begin{array}{*{20}{c}} {}&{\text{A}}&:&{\text{B}} \\ {{\text{Profit}}}&5&:&9 \\ {{\text{Time}}}&8&:&{12} \\ {}&{\text{A}}&:&{\text{B}} \\ {}&5&:&9 \\ {}&2&:&3 \\ {{\text{Capital}}}&{\frac{5}{2}}&{}&{\frac{9}{3}} \\ {\frac{{{\text{Profit}}}}{{{\text{Time}}}}}&5&:&6 \end{array}\]
$$\eqalign{ & 6 \to 36,000 \cr & 5 \to \boxed{30,000} \cr} $$