Teacher:In this task, you need to answer the given multiple-choice question on the physics. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.
Teacher: Now, understand the problem? Solve this instance: Problem: a can do a piece of work in 9 days . when he had worked for 2 days b joins him . if the complete work was finished in 8 days . in how many days b alone can finish the work ? 
Options: a ) 18 , b ) 77 , c ) 66 , d ) 54 , e ) 12
Student:
d