In a certain code, '467' means 'leaves are green' ; '485' means 'green is good' and '639' means 'they are playing'. Which digit stands for 'leaves' in that code ?
In the first and second statements, the coommon code digit is '4' and the common word is 'green'.
So, '4' means 'green'.
In the first and third statements, the common digit is '6' and the common word is 'are'.
So, '6' means 'are'.
Thus, in the first statements, '7' means 'leaves'.