The sum of the numbers of boys and girls in a school is 150. If the number of boys is x, the number of girls becomes x% of the total number of students. The number of boys is: 

The ratio of the ages of two persons is 4 : 7 and the age of one of them is greater than that of the other by 30 years. The sum of their ages ( in years ) is 

Find the square root of  $$ {k+l+m+n+2\sqrt{ml+mk}+2\sqrt{mn}+2\sqrt{kn+ln}}$$

In two types of brass ratio of copper and zinc are 8: 3 and 15: 7 respectively. The ratio in which these two types of brass should be mixed, so that the ratio of copper and zinc in this new type of brass become 5: 2 is 

A and B together can do a certain work in x days. Working alone, A and B can do the same work in (x+8) and (x+18) days, respectively. A and B together will complete $$ {5\over 6}$$ of the same work in;

A man gives 20% of his money to his eldest son, 30% of remaining he gives to his younger son. 10% of the remaining he gives in a school for poor boys still he has Rs.100.80. Find his total sum. 

If tanθ=1/5 then the value of Cosec²θ=?

The shadow of a tower when the angle of elevation of the sun is 45 °, is found to be 10 m longer that when it was 60 °. The height of the tower is