$$6\frac{3}{8}+4\frac{5}{6}=6\frac{9}{24}+4\frac{20}{24}=11\frac{5}{24}\ell$$ 
Tiantian drank $$6\frac{3}{8}$$ litres of water. Matthew drank $$4\frac{5}{6}$$ litres of water. How many litres of water did the both of them drink altogether? Give your answer as a mixed number in the simplest form. 

- $$10\frac{4}{7}\ell$$ 
- $$10\frac{5}{8}\ell$$ 
- $$10\frac{15}{24}\ell$$ 
- $$11\frac{5}{24}\ell$$ 