Simplify the complex fraction StartFraction StartFraction 1 over x EndFraction over StartFraction 2 over y EndFraction EndFraction.

To simplify the complex fraction, we will first simplify the numerator and denominator separately before dividing them.

Numerator:
StartFraction 1 over x EndFraction

Denominator:
StartFraction 2 over y EndFraction

Now, we can simplify the numerator and denominator further:
Numerator:
StartFraction 1 over x EndFraction = 1/x

Denominator:
StartFraction 2 over y EndFraction = 2/y

Now, we divide the simplified numerator by the simplified denominator:
StartFraction 1/x EndFraction divided by StartFraction 2/y EndFraction

Multiplying the numerator by the reciprocal of the denominator:
StartFraction 1/x EndFraction * StartFraction y/2 EndFraction = y/2x

Therefore, the simplified complex fraction is y/2x.