The Decibel

Useful fact...

If one power is 7.5 watts and
the other 1.3 watts,
then LOG(7.5/1.3) = +0.761 and LOG(1.3/7.5) = -0.761

So you can calculate the ratio either way and get the same absolute value of LOG.
Simply remember that a 'lossy' device is represented by a - sign in further calculation.