In a computer game, there are builders and destroyers. Together there are 20 of them. Some of them try to build a wall around a castle while the rest try to demolish it. Each of the builders can build the wall alone in 15 hours while any of the destroyers can demolish it in 10 hours. If all 20 builders and destroyers are made active when there is no wall and the wall gets built in 3 hours, how many of them are destroyers?

G is twice as fast as S in doing work. If G can do a work in 30 days less than S, how many days will they take to complete the work together?

X can complete 5/7 part of a work in 10 days and Y can complete 3/4 part of the same work in 9 days. In how many days will both complete 13/21 part  of the total work?

P can do a work in 10 days. Q can do the same work in 15 days. If they work together for 5 days, how much of the work will they complete?

P can make a table in 16 days while Q can make it in 20 days. Q started the work and did that work for 5 days. In how many days P can complete the remaining work?

S and T can finish a work in 50 days. They worked together for 20 days and then left. How much of the work is left?

Type 1 workers are 2.5 times as efficient as type 2 workers. Twelve Type 1 workers can complete a task in 10 days. How many days would it have taken 4 Type 1 and 15 Type 2 workers to do the same work?

P, Q and R alone can complete a work in 12, 15 and 20 days respectively. In how many days will they together complete the same work?

A, B and C can complete the work in 4, 5 and 6 hours respectively. If they all work together and receive Rs. 777 as wages then find the share of A.