A,B and C are assigned a piece of work which they can complete by working together in 15 days. their efficiencies(measured in terms of rate of doing work) are in the ratio of 1:2:3. After 1/3rd of the work is completed,one of them has to be withdrawn due to budget constraint. Their wages per day are in the ratio of 3:5:6.The number of days in which the remaining two persons can complrte the work (at optimal cost) is.....