Sara can finish a work in 18 days and Tara can complete the same work in 15 days. Tara worked for 10 days and left the job. In how many days can Sara finish the remaining work alone?

Correct option is A

Given:
Sara can finish the work in 18 days.
Tara can finish the work in 15 days.
Tara worked for 10 days and then left.
Formula Used:
Work done by a person in 1 day = 1 / (number of days required to complete the work)
Total work done = Work rate × Time
Solution:
Calculate the work done by Tara in 10 days:
Work rate of Tara = 1 / 15
Work done by Tara in 10 days = (1 / 15) × 10 = 10 / 15 = 2 / 3
Calculate the remaining work:
Total work = 1
Remaining work = 1 - (2 / 3) = 1 / 3
Calculate the time taken by Sara to complete the remaining work:
Work rate of Sara = 1 / 18
Time taken by Sara to complete the remaining work = (Remaining work) / (Work rate of Sara)
Time = (1 / 3) / (1 / 18) = (1 / 3) × 18 = 6 days
Answer: 6
Alternate Method: