Both ways work.

Just to clarify: (-1)/(2)=(1)/(-2)

The proof: you know that: (1/2)x(2/3)=(1x2)/(2x3)=2/6=1/3

and you know that: -1x-1=1

and you know that: -1/-1=1

then: (-1)/(2)=(-1)/(2)

multiply both sides by 1: (-1)/(2)x1=(-1)/(2)x(-1)/(-1)

thus: (-1)/(2)=(-1x-1)/(2x-1)

therefore: (-1)/(2)=(1)/(-2)