In a certain code language, '-' represents 'x', '÷' represents '+', '+' represents '÷' and 'x' represents '-'. Find out the answer to the following question.
In a certain coding language, 'Ginger is a root' is written as 4123, 'A tree has a root' is 75422 and 'Tree is green' is 385. Which digit represents 'root'?