The average age of a class of 40 students and a teacher reduces by 0.5 years, if we exclude the teacher. If the initial average age is 18 years, then what is the age of the teacher?

The printed price of a book is 320. A retailer pays 244.80 for it. He gets successive discounts of 10% and an another rate. His second rate is-

A dealer buys a table listed at ₹ 1,500 and gets successive discounts of 20% and 10%. He spends ₹ 20 on transportation and sells at a profit of 20%. Find the selling price of the table (in rupee). 

A dealer buys a table listed at Rs 1,500 and gets successive discounts of 20% and 10%. He spends Rs. 20 on transportation and sells it at a profit of 20%. The selling price of the table is

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: 

If on a marked price the difference of selling prices with a discount of 30% and two successive discounts of 20% and 10% is 72, then the marked price (in rupees) is  

The difference between a discount of 30% on ₹ 2,000 and two successive discounts of 25% and 5% on the same amount is 

The difference between B a discount of 30% on ₹2,000 and two successive discounts of 25% and 5% on the same amount is