A can contains a mixture of two liquids A and B in the ratio 7:5. When 9 litres of mixture are drained off and the Can is filled with B, the ratio of A and B becomes 7:9. How many litres of liquid A was contained by the Can initially?

What is the value of $${cos^2A\over {1+sinA}}$$?

The third proportional of two numbers 4 and 20 is

An angle is four times its complementary angle. What is the measure of the angle?

In a class of 50 students there are 27 girls. The average weight of these girls is 45 kg and average weight of the full class is 49.6 kgs. What is the average weight of the boys of the class?

The average weight of Sudesh, Jyothi and Ritu is 89 kg. If the average weight of Sudesh and Jyothi be 98 kg and that of Jyothi and Ritu be 83 kg, then the weight of Jyothi is

$$ {{2^n+2^{n-1}}\over {2^{n+1} -2^n}}=?$$

If $$ {x+{1\over x}}=2$$ then find out the value of $${2x^2+2}\over{3x^2+5x+3}$$