X can finish a work in 18 days. Y can finish the same work in 15 days. Yworked for 5 days and left the job. how many days does X alone need to finish the remaining work?  Choose the correct option.
A) 12
B) 5
C) 6
D) 8
E) 9

Rationale: work done by x in 1 day = 1 / 18 work done by y in 1 day = 1 / 15 work done by y in 5 days = 5 / 15 = 1 / 3 remaining work = 1 – 1 / 3 = 2 / 3 number of days in which x can finish the remaining work = ( 2 / 3 ) / ( 1 / 18 ) = 12 a
Answer: A