If a(x + y) = b(x - y) = 2ab, then the value of 2(x2 + y2)

18 men or 36 boys working 6 hours a day can plough a field in 24 days. In how many days will 24 men and 24 boys working 9 hours a day plough the same field ?

If θ is acute angle and sin(θ+18°)= 1/2, then the value of θ in circular measure is

O is an centre of a circle. P is an external point of it at distance of 13cm from O. The radius of the circle is 5cm. Then the length of a tangent to the circle from P upto the point of contact is

If x + 1/x = √13, then 3x(x2-1) equal to

If x = 1/(√2+1) then the value of x2 + 2x - 1 is

A money lender lends Rs. 400 for 3 years to a person and lends Rs. 500 for 4 years to the other person at the same rate of simple interest. If altogether he receives Rs. 160 as interest, what is the rate of interest per annum ?

A car moving in the morning fog passes a man walking at 4km/h. in the same direction. The man can see the car for 3 minutes and visibility is upto a distance of 130m. The speed of the car is :