Direction : What value should come in the place of question mark (?) in the following questions?

$$({144\over16}×{828\over 9})=?+325 $$

If Sonu is driving a car with a speed of 20 m/s, then in what time will Sonu cover a distance of 936 km?

The ratio of the areas of two isosceles triangles having the same vertical angle is 1 : 9.The ratio of their heights is -

Two pipe can fill a cistern in 3 hours and 4 hours respectively and a waste pipe can empty it in 2 hours. If all  the three pipes are kept open, then the cistern will be filled in

A train of length 212 meter is running at 45 km/h. In what time (in seconds) will it cross a platform of length 188 meter?

Mohan bought 25 books for Rs. 2,000 and sold them at a profit equal to the selling price of 5 books. The selling price of 1 book is: 

Two numbers are in the ratio 3 : 4. Their L.C.M. is 84. The greater number is 

A semicircle is folded to make a cone. Find the height (in cm) of the cone if diameter of the semicircle is 28 cm?