If the duty on an article is reduced by 40% of its present rate by how much per cent must its consumption increase in order that the revenue remains unaltered?

The marked price of one pen is '₹x'. The selling price of one packet of 'x' pens, after a discount of 15%, ₹1360. What is the value of 'x'?

Average weight of 25 students of a class is 50 kg. If the weight of the class teacher is included, the average is increased by 1 kg. The weight of the teacher is 

The cost price of 27 articles is the same as the selling price of 18 articles. What is the gain percentage?

What approximate value should come in the place of question mark (?) in the following question?

{44.95 - (16.97 × 2.93 - 2.99 × 1.92)} = ?

A and B are solutions of acid and water. The ratio of water and acid in A and B are 4 : 5 and 1 : 2, respectively. If x literes of A is mixed with y litres of B, then the ratio of water and acid in the mixture becomes 8 : 13. What is x : y ?

A and B start moving towards each other from places X and Y, respectively, at the same time on the same day. The speed of A is 20% more than that of B. After meeting on the way, A and B take p hours and 72 hours, respectively, to reach Y and X, respectively. What is the value of p?

A spherical metallic shell with 6 cm external radius weighs 6688 g. What is the thickness of the shell if the density of metal is 10.5 g per cm3? (Take л = 22/7)