The top scale supports only me and reads my weight (in either Newtons or pounds or stone but never in kg), the bottom scale reads the sum of the two things it supports, namely, me and the top scale.
(the two things; supports; it) (the bottom scale; reads; the sum of the two things) Context(the bottom scale reads,List([107, 129))):(The top scale; supports; only me)
the bottom scale reads,List([107, 129))
the two things the bottom scale The top scale
supports reads supports
it
the sum of the two things
only me