Giải thích các bước giải:
A = $\frac{5}{6}$ + $\frac{5}{12}$ + $\frac{5}{20}$ + $\frac{5}{30}$ + $\frac{5}{42}$
A = $\frac{5}{2.3}$ + $\frac{5}{3.4}$ + $\frac{5}{4.5}$ + $\frac{5}{5.6}$ + $\frac{5}{6.7}$
A = $\frac{5}{2}$ - $\frac{5}{3}$ + $\frac{5}{4}$- $\frac{5}{4}$ + ... + $\frac{5}{6}$ - $\frac{5}{7}$
A = $\frac{5}{2}$ - $\frac{5}{7}$
A = $\frac{25}{14}$