Calculate: $$\left( \frac{9+10+11}{8}-\frac{10+11+12}{9}+\frac{11+12+13}{10}-\frac{12+13+14}{11} \right)$$$$\div \left( \frac{1}{8}-\frac{1}{9}+\frac{1}{10}-\frac{1}{11} \right)$$． 
Overseas Competition->Knowledge Point->Calculation Modules->Fractions->Basic Understanding of Fractions->Using Common Factors to Simplify Fractions