10 peoples can build a wall in 12 days. six peoples, each only half as efficient as those in the first group, will be able to complete 3/5 of such a wall in?

24

Let the total work done be 120 units. Work done by 10 people per day = 120/12 = 10 units /day Work done per person = 10/10 = 1 unit/day In the next team, each person is half as efficient as the previous one. Hence work done per person = 0.5/day 3/5 * 120 = 72 , work which needs to be done by team 2 Hence time taken will be, 6 * 0.5 * x = 72 => x = 24