Both X and Y are zinc-copper mixtures. The ratios of zinc to copper in X and Y are 5:7 and 8:7, respectively. If X and Y are mixed in a 1:1 ratio, what is the ratio of zinc to copper in the mixture?
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A$$\frac{11}{12}$$
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B$$\frac{13}{14}$$
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C$$\frac{32}{35}$$
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D$$\frac{44}{47}$$
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E$$\frac{57}{63}$$
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正确答案: E