The angle of elevation of the top of a tower from the point P and Q at a distance of 'a' and 'b' respectively from the base of the tower and in the same straight line with it are complementary. The height of the tower is:
A, B and C can do one-third of a work in 15 days, 30 days and 10 days, respectively. A started the work. C joined him after 1 day and B joined them after 3 days of the beginning. For how many days did C work?
The angle of elevation of the top of a tower from a point A on the ground is 30°. On moving a distance of 20 metres towards the foot of the tower to a point B, the angle of elevation increases to 60°. The height of the tower is
A shopkeeper buys two books for Rs.300. He sells the first book at a profit of 20% and the second book at a loss of 10%. What is the selling price of the first book, if, in the whole transaction there is no profit or no loss?