Alloy A contains metals x and y only in the ratio 5 : 2 and alloy B contains these metals in the ratio 3 : 4. Alloy C is prepared by mixing A and B in the ratio 4 : 5. The percentage of x in alloy C is:

\[\begin{array}{*{20}{c}} {}&x&:&y&{} \\ {A \to }&{{5_{ \times 4}}}&:&{{2_{ \times 4}}}&{ = {7_{ \times 4}}} \\ {B \to }&{{3_{ \times 5}}}&:&{{4_{ \times 5}}}&{ = {7_{ \times 5}}} \end{array}\]
$$\eqalign{ & C \to A + B \to 35 + 28 = 63 \cr & \% \,{\text{of }}x{\text{ in aloy C}} = \frac{{35}}{{63}} \times 100 = 55\frac{5}{9}\% \cr} $$