What is the ratio of the electricity bill paid by Manu in the month of April to the mobile phone bill paid by Ravi in the month of June?

In which months respectively did Manu pay the second highest mobile phone bill and the lowest electricity bill?

What is the difference between the mobile phone bill paid by Ravi in the month of May and the laundry bill paid by Dev in the month of March?

What is the average electricity bill paid by Manu over all the five months together?  

What is the total amount of bill paid by Dev. in the month of June for all the four commodities?

In teaching profession if three - fifths of the teachers are not permenent, what is the number of permanent teachers in the teaching profession?