If the work done by (x-1) men in (x+1) days and the work done by (x+2) men in (x-1) days is in the ratio of 9 : 10, then x is equal to

12 men can complete one-third of the work in 8 days. In how many days can 16 men complete that work?

An exterior angle of a regular polygon is 72^o. The sum of all the interior angles is -

In a certain year, the average monthly income of a person was Rs.3,400. For the first eight months of the years, his average monthly income was Rs. 3,160 and for the last five months, it was Rs.4,120. His income in the eighth month of the year was: 

The distance between two pillars is 120 meters. The height of one pillar is thrice of the other pillar. The angles of elevation of their tops from the midpoint of the line connecting their feet are complementary to each other. The height (in metres) of the pillar is (use : √3 = 1.732 )

12 × 15 + 27 – ? = 28% of 400

A shop keeper purchased a chair marked at ₹ 800, at two successive discounts of 10 % and 15% respectively. He spent ₹ 28 on transportation and sold the chair for ₹ 800. His gain percent is: 

In ∆ABC, AD is the internal bisector of ∠A, meeting the side BC at D. If BD = 5 cm, BC = 7.5 cm, then AB : AC is