Answer:
That brand’s heaviest laptop weighs less, not more, than the daily newspaper.
Explanation:
Commas are necessary before and after the words not more. Not more is another way to say less. When you use a word and then want to describe or explain it in other words (just like in this case), that description/explanation needs to be separated from the rest of the sentence by commas. This is why the given sentence should look like this:
That brand’s heaviest laptop weighs less, not more, than the daily newspaper.
