Concept: The question tests on the area of Rates(Time and Work)
Solution:
Ram does 40% = 2/5th of the work in 12 days
To complete the work, time taken = 1∗12/(2/5) =30 days
The remaining work is 60% = 60 /100 = 3/5th of the work
Working together they finish 3/5th of the work in 12 days
Therefore to do the complete work = 1∗12/(3/5)= 20 days
Work done by Ram in 1 day = 1/30
Let Ravi take x days to finish the work. Work don by Ravi in 1 day = 1/x
1/30+1/x=1/20
1/x=1/20−1/30=3−2/60=1/60
Ravi takes 60 days to complete the work which is twice the time Ram takes
Ram is 100% more efficient than Ravi
Option B