Answer:
A
Step-by-step explanation:
Given
a = [tex]\frac{1}{x}[/tex] - [tex]\frac{1}{y}[/tex] = [tex]\frac{y-x}{xy}[/tex] ← as a single fraction
Thus
[tex]\frac{1}{a}[/tex] = [tex]\frac{1}{\frac{y-x}{xy} }[/tex] = [tex]\frac{xy}{y-x}[/tex] → A
