10 women take 16 days to complete a work which can be completed by 6 men in 8 days. 12 men started working and after 2 days 6 men left, and 5 women joined them. In how many days will the work be completed?

X , Y and Z can complete a work in 5 days, 15 days and 30 days, respectively. In how days can the work be completed if X is assisted by Y and Z together, on every second day?

Abraham can complete a work in 9 days, while Andrew can complete the same work in 6 days. In how many days can they complete the work if they work together?

A, B and C can finish a work in 15 days working alternately in the same order. The efficiency of A is the same as that of B, and the efficiency of C is equal to that of A. In how many days will the work be finished if they work alternately in the order C, A and B?