-- Reflecting across the x-axis makes all the x-coordinates the negative of
what they were before the reflection. The y-coordinates don't change.
-- Translating 2 units up makes all the y-coordinates 2 greater than
they were before the translation. The x-coordinates don't change.
You didn't give us a list of new coordinates, so there's nothing
to match with.
In the first one it would be (21-8)-6=7.
and in the second one it would be 21-(8-6)=19
