Two vessels contain milk and water in the ratio of 9 : 7 and 5 : 11.  If the both vessels are mixed in ratio of 1 : 1.  Find the ratio of milk and water in new mixture.

1 : 3 8 : 9 7 : 9 9 : 7

7 : 9

M    :    W I   →   9    :     7   =   16 II  →   5    :     11  =   16           14   :    18           (already in the ratio 1 : 1, so add I & II)   =      7   :    9