A =\(\frac{\frac{12}{13}+\frac{12}{131}-\frac{12}{1313}+\frac{12}{13131}}{\frac{15}{13}+\frac{15}{131}-\frac{15}{1313}+\frac{15}{13131}}=\frac{12.\left(\frac{1}{13}+\frac{1}{131}-\frac{1}{1313}+\frac{1}{13131}\right)}{15.\left(\frac{1}{13}+\frac{1}{131}-\frac{1}{1313}+\frac{1}{13131}\right)}=\frac{12}{15}=\frac{4}{5}\)
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