Let #f(w)=(w-6)/w#
The domain of #f(w)# is #D_f(w)=RR-{0}#
Let's build the sign chart
#color(white)(aaaa)##w##color(white)(aaaa)##-oo##color(white)(aaaaa)##0##color(white)(aaaaa)##6##color(white)(aaaaaa)##+oo#
#color(white)(aaaa)##w##color(white)(aaaaaaaa)##-##color(white)(aa)##||##color(white)(aa)##+##color(white)(aaaa)##+#
#color(white)(aaaa)##w-6##color(white)(aaaaa)##-##color(white)(aa)##||##color(white)(aa)##-##color(white)(aaaa)##+#
#color(white)(aaaa)##f(w)##color(white)(aaaaaa)##+##color(white)(aa)##||##color(white)(aa)##-##color(white)(aaaa)##+#
Therefore,
#f(w)<=0# when #x in ]0,6]#