Find the exact value of the following question:

$$ 8\sqrt{?}÷14×3+9=21$$

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

Mr. Dev sold a bus for Rs. 2210 with a loss of 15 %. At what price should the bus be sold to get a profit ot 15 %?

60% boys are failed in History and 65% boys are failed in Geography while total 30% boys are failed in both the subjects. If total 1200 boys appeared in the examination then total how many boys are passed?

A man wanted to sell an article with 20% profit: but he actually sold at 20% loss for Rs. 480, At what price he wanted to sell it to earn the profit? 

Directions : What will come in the place of the question mark (?) in the following number series?

60.75, 40.5, 27, 18, 12, ?

Direction: Study the following graph and answer the questions based on it.

In how many years was the production of fertilizers more than the average production of the given years? 

The distance traveled by three cars in the ratio of 1: 2: 3. If the travel time ratio is 3: 2: 1, what is the ratio of their speed?