Select the option that is related to the third letter-cluster in the same way as the second letter-cluster is related to the first letter-cluster.
MNTK : HIOF : : RUNA : ?
The average salary of the entire staff in an office is ₹3,560 per month. The average salary of the officers is ₹5,400 per month and that of the non-officers is ₹2,600 per month. If the number of officers is 12, find the number of non-officers in the office.