George takes 8 hours to copy a 50-page manuscript while Sonia can copy the same manuscript in 6 hours. How many hours would it take them to copy a 100-page manuscript, if they work together ?

• A. $6\frac{6}{7}\,\,{\text{hours}}$$
• B. ${\text{9 hours}}$$
• C. $9\frac{5}{7}\,\,{\text{hours}}$$
• D. ${\text{14 hours}}$$