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. 
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$$6\frac{3}{8}+4\frac{5}{6}=6\frac{9}{24}+4\frac{20}{24}=11\frac{5}{24}\ell$$ 