If xy=4, x/y=81, for positive numbers x and y, y=? Options:	A) 1/2	B) 2	C) 2/9	D) 3	E) 1/6
Very easy question. 2 variables and 2 easy equations.   xy=4 ---&gt; x=4/y - (i)   x/y=81 ---&gt; replacing (i) here ---&gt; 4/(y^2)=81 ---&gt; y^2=4/81 ---&gt; y=2/9 or -2/9   The question states that x and y are positive integers. Therefore, y=2/9 is the answer.   Answer 2/9.
<result>C</result>
If xy=4, x/y=81, for positive numbers x and y, y=?