The sum of all percentages is always 100 %
%converted into light + % converted into heat = 100 %
11.1% + % converted into heat = 100%
% converted into heat = 100% - 11.1% = 88.9%
So, if efficiency is 11.1%, then 88.9% of the power supplied is wasted and converts into heat.
100%_______8W
88.9%_______x = 88.9*8W/100= 7.112 W
So, if the supplied power is 8 W, and 88.9% of the power converts into heat, then 7.112 W are converted into heat.