Step 1: A completes 1 unit of work in 12 days.
A's work rate = 121 unit per day.
Step 2: B's capacity is 60% more than A's.
60% = 10060=53.
B's work rate = (1+53)×121 unit per day
=58×121 unit per day
=608 unit per day
=152 unit per day.
Step 3: Time taken by B to complete 1 unit of work
=1521 days
=215 days
=7.5 days.
7.5days