What is the value of $$ {\sqrt{625}+\sqrt{484}}$$

From a point 20 m away from the foot of a tower, the angle of elevation of the top of the tower is 30°. The height of the tower is

The average of 6 numbers is 20. If a number is removed then average becomes 15. In place of removed number by adding a number 39 the average of new 6 number will be__

If the height of a given cone be doubled and radius of base remains the same, the ratio of the volume of the given cone to that the second cone will be -

If $$ {1\over3} ({12x\over5}-{1\over2})+{6\over5}={7\over6}$$ then what is the value of x?

In a class, there are 30 girls and 15 boys and total average weight of class is $$47{7\over15}$$ kg. The total average weight of boys is 58 kg. Find the approximate average weight of girls. 

Find the value of   $$ {(0.75)^3\over1-.75}+[0.75+(0.75)^2+1]$$

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