Person A works twice as fast as person B. Person B can complete a piece of work independently in 12 days. Find the number of days taken by person A and B together to finish the work.
A rate = 1 job /6 days = 1/6
B rate = 1 job /12 days = 1/12
1 job / (1 job /6days + 1 job/ 12 days)
1/(1/6 + 1/12) = ? days
can you do it from here???