Đáp án:
=$\frac{10}{11}$ : ($\frac{2}{3}$ - $\frac{2}{5}$ + $\frac{2}{5}$ - $\frac{2}{7}$ + $\frac{2}{7}$ - $\frac{2}{9}$ + $\frac{2}{9}$ - $\frac{2}{11}$)
= $\frac{10}{11}$ : ($\frac{2}{3}$ - $\frac{2}{11}$)
= $\frac{10}{11}$ : $\frac{2×11+ 2×3}{11×3}$
= $\frac{10}{11}$ × $\frac{11×3}{2×11+ 2×3}$
= $\frac{10×3}{2×14}$
= $\frac{15}{14}$