Answer
$\dfrac{y}{x + y}$
Work Step by Step
Do the addition in the denominator first.
Find the least common denominator (LCD) of the two terms of the denominator:
$\dfrac{1}{\frac{y}{y} + \frac{x}{y}}$
Perform the addition in the denominator:
$=\dfrac{1}{\frac{x + y}{y}}$
Rewrite this fraction as a division problem:
$=1 \div \dfrac{x + y}{y}$
To divide one fraction by another, multiply the first fraction by the reciprocal of the second fraction:
$=1 \times \frac{y}{x + y}$
Multiply to simplify:
$=\dfrac{y}{x + y}$