how do we know when to use it?

I solved Q5 the way he did it in the beginning, he said it was accurate. But gave another example to do it, which to me is a bit more complicated. Should I stick to how I make sense of it? Can I keep doing it like that?

@sophialeehicks166 thats what i got from it aswell

@Le Castille the example started off

M > N and O

he did the contrapositive which was /N or /O > M

Remember that because it started off with "and" you switch to "or"

he did that because of the de morgan law

@DannistyP20255 link is in the comments!

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@OliviaWatkin pls do!

@cnp_22 not at all!

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