-6:2 = 12:4
-5:8 = 10:16
We use ratios everywhere and not just in our textbooks, there other places too like any sport scoreboard, like perhaps in grocery stores, and many others.
We can also reduce ratios to their lowest terms, like so:
-12:8 = 6:4 = 3:2 -and 3 to 2 is your lowest term now.