The product of two numbers x and y is twice the sum of the numbers. What is the sum of the reciprocals of x and y?
A
2/3
B
3/4
C
3/7
D
1/2
Correct Answer: 1/2
Hints : xy = 2 ( x + y) xy/ x + y = 2 x + y/xy = 1/2 1/x + 1/y = 1/2