A person wants to take a bath, and fills the tub with 50 L of water at a temperature of 38o C after receiving a phone cell. The bath water had cooled by10 o C. How much more hot water at 80 o C must that person add to return the bath to desired temperature........... L 

a) 5 

b) 6.25 

c) 9.6 

d) 11.9