The greatest common factor of two co-prime numbers will be

if x⁴+y⁴+x²y²=21 and x²+y²-xy=7, then what is the value of  $${x\over y}+{y\over x}=?$$

A person covered some distance at some speed. If he traveled a distance of 3 km / h more, it took him 40 minutes less time. If he had covered the distance at a speed of 2 km / h less, he would have taken 40 minutes more. The distance (in km) is

Successive discounts of 10% and 30% are equivalent to a single discount of : 

A tank can be filled with water by two pipes A and B together in 36 minutes. If the pipe B was closed after 30 minutes, the tank is filled in 40 minutes. The pipe B can alone fill the tank in?

Sound travels 330 meters in one second. When the sound is heard 10 seconds after the lightning flashes, then at what distance will the cloud be?

The diagonal of a right angle isosceles triangle is 5 cm. Its area will be

An isosceles triangle ABC is right angled at B.D is a point inside the triangle ABC. P and Q are the feet of the perpendiculars drawn from D on the side AB and AC respectively of ∆ ABC. If AP = a cm, AQ = b cm and ∠BAD = 15°, sin 75°=