Urči součet řady \( \large \sum\limits_{n=1}^\infty \left[ 8 \cdot \left( \Large \frac{7}{8}\large \right) ^{n-1}\right] \).
\( \large s = 56 \)
\( \large s = 64 \)
\( \large s = 72 \)
\( \large s = 60 \)