The ratios of copper to zinc in alloys A and B are 3 : 4 and 5 : 9, respectively. A and B are taken in the ratio 2 : 3 and melted to form a new alloy C. What is the ratio of copper to zinc in C?

$$\eqalign{ & A \to 3:4 = {7_{ \times 2 \times 2}} \cr & B \to 5:9 = {14_{ \times 3}} \cr & {\text{Copper}}:{\text{Zinc}} \cr & \,\,\,\,\,\,\,\,\,\,\,\,{\text{12}}\,\,\,{\text{:}}\,\,\,{\text{16}} \cr & \,\,\,\,\,\,\,\,\,\,\,\,{\text{15}}\,\,\,{\text{:}}\,\,\,{\text{27}} \cr & \,\,\,\,\,\,\,\,\,\,\overline {\,\,27\,:\,43\,\,} \cr} $$