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

2549.99 - [509.99 - {269.97 - (89.9 - 79.9 + 69.9)}] = ?

Sujata marks the marked price of an article at 36% above the cost price and allows 40% discount on the marked price then what is the loss percentage?

The height of a solid cylinder is 30 cm and the diameter of its base is 10 cm. Two identical conical holes each of radius 5 cm and height 12 cm are drilled out. What is the surface area (in cm²) of the remaining solid?

The marked price of an article is 40% above its cost price. If its selling price is $$73{1\over 2}\%$$ of the marked price, then the profit percentage is

A trader allows a trade discount of 20% and a cash discount of $$6{1\over4}\%$$ on the marked price of the goods and gets a net gain of 20% of the cost. By how much above the cost should the goods be marked for the sale? 

The expression   $${15(\sqrt { 10}+\sqrt { 5})\over \sqrt { 10}+\sqrt { 20}+\sqrt { 40}-\sqrt { 5}-\sqrt { 80}     }$$ is equal to:

The following table shows the number of bundles of iron bars of 5 different brands sold from a shop during a given week.

The number of iron bars in each bundle of B1 and B3 is 5. The number of iron bars in each bundle of B2, B4 and B5 is 4. What is the total number of iron bars sold from the shop during that week of all the 5 brands taken together?

What is the area (in cm² ) of an equilateral triangle of side 20 cm?