Permutation concept question

Hi I’m new to the forums sorry if this isn’t the proper section for a post like this.
I’m currently trying to study permutations and came across this:

But using this technique for another question I found here I got (5 * 4 * 3)/ (3 * 2 * 1)


gives a different answer. Is one of the explanations incorrect? Or am I doing something wrong?

the above post is about combination while the lower one is about permutation