25. If 20 men working 7 hours a day can do a piece of work in 10 days, in how many days will 15 men working for 8 hours a day do the same piece of work ?

26. If 40 person consume 60 kg. of rice in 15 days, then in how many days will 30 persons consumer 12 kg. of rice :

27. If 3 person weave 168 shawls in 14 days, how many shawls will 8 persons weave in 5 days ?