One acute angle of a right-angled triangle is double the other. If the length of its hypotenuse is 10 cm, then its area is

In 64 liter of pure milk, 20 liter of water is mixed and then $$ {1\over 4}{th}$$ of the mixture is taken out. When x liter of water is added again then ratio of water to that of the milk becomes 1:2. Find value of x?

The ages of Shyam and Mohan are in the ratio of 11: 13 respectively after 7 years the ratio of their ages will be 20: 23. What is the difference in years between their ages?

ABC is an isosceles triangle with AB = AC, A circle through B touching AC at the middle point of Q, intersects AB at P. Then AP : AB is : 

$$ {a^2-b^2-2bc-c^2}\over{a^2+b^2+2ab-c^2}$$ is equal to

The length, breadth and height of a room are in the ratio 7:3:1. If the breadth and height are doubled while the length is halved, then by what percent the total area of the 4 walls of the room will be increased?

Two cars travel from city A to city B at a speed of 36 and  48 km/hr respectively. If one  car takes 3 hours lesser time  than the other car for the journey, then  the distance between City A and  City B is

The ratio of present ages of Ratna and Shantanu is 5:4. After 19 years, the ratio of their ages will be 10:9. What is Ratna's present age?