12 pumps working 6 hours a day can empty a completely filled reservoir in 15 days. How many such pumps working 9 hours a day will empty the same reservoir in 12 days?

If $$ {x+{1\over 16x}}=1 $$, then $$ {64x^{3}+{1\over 64x^{3}}}$$ will be:

In a group of students, 70 % can speak English and 65 % can speak Hindi. If 27 % of the students can speak none of the two languages, then what percent of the group can speak both the languages? 

The average speed of a train is 3 times the average speed of car. The car covers a distance of 520 km in 8 hours. How much distance will the train cover in 13 hours?

If 5500 copies are published and the transportation cost on them amounts to Rs. 82,500, then what should be the selling price of the book so that the publisher can earn a profit of 25%?

5 number whose average is 76, the first is 3/7 times the sum of other 4. the first number is: 

Either 8 men or 17 women can paint a house in 33 days. The number of days required to paint three such houses by 12 men and 24 women working at the same rate is: