\(=\dfrac{\dfrac{8}{8}-\dfrac{8}{7}+\dfrac{8}{11}+\dfrac{8}{15}}{\dfrac{7}{8}-\dfrac{7}{7}+\dfrac{7}{11}+\dfrac{7}{15}}=\dfrac{8}{7}\)
\(\dfrac{1-1\dfrac{1}{7}+\dfrac{8}{11}+\dfrac{8}{15}}{0,875-1+\dfrac{7}{11}+\dfrac{7}{15}}\)
\(=\dfrac{1-\dfrac{8}{7}+\dfrac{8}{11}+\dfrac{8}{15}}{\dfrac{875}{1000}-1+\dfrac{7}{11}+\dfrac{7}{15}}\)
\(=\dfrac{1-\dfrac{8}{7}+\dfrac{8}{11}+\dfrac{8}{15}}{\dfrac{7}{8}-1+\dfrac{7}{11}+\dfrac{7}{15}}\)
\(=\dfrac{\dfrac{8}{8}-\dfrac{8}{7}+\dfrac{8}{11}+\dfrac{8}{15}}{\dfrac{7}{8}-\dfrac{7}{7}+\dfrac{7}{11}+\dfrac{7}{15}}\)
\(=\dfrac{8.\left(\dfrac{1}{8}-\dfrac{1}{7}+\dfrac{1}{11}+\dfrac{1}{15}\right)}{7.\left(\dfrac{1}{8}-\dfrac{1}{7}+\dfrac{1}{11}+\dfrac{1}{15}\right)}\)
\(=\dfrac{8}{7}\)
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