In the following question, four number pairs are given. The number on left side of (–) is related to the number of the right side of (–) with some Logic/Rule/Relation. Three are similar on basis of same Logic/Rule/Relation. Select the odd one out from the given alternatives.
A and B together do a job in 6.75 days and A could do the job in 9 days if he worked alone. How many days would B take to do the job if he worked alone?