Your solution still answers the wrong question and even results in a contradiction: the initial statement was "say there's a [power] saving of 2W." Your conclus

Your solution still answers the wrong question and even results in a contradiction: the initial statement was "say there's a [power] saving of 2W." Your conclusion would be that there's a power saving of 0.167W, which in incoherent with the initial assumption. Context is very important.