I am having a hard time understanding conjunction "and", and why the necessary conditions are able to be separated. I understand that the two events are independently necessary, but does that mean if one of the necessary conditions is met then it is valid?

For example, the first conditional saying MG ---> benefits and intention. These two necessary conditions could be separated. Would that mean that if the actions benefit others but was NOT performed with that intention the conditional statement is valid?

If not, why are you able to separate the conditions? This might not be that significant, but I want to have a complete understanding and this is tripping me up.

Trying to gain a deeper understanding of conditional logic without relying on words, so from my understanding "An engaging plot will guarantee a novel's commercial success" does NOT mean that if the novel has commercial success it has an engaging plot.

That would be an example of mistaking sufficiency for necessity.

For number 1, when connecting the second and third premise with the first, wouldn't combining the two /meth make it a positive meth?

Since heroin -> LSD -> /meth connects to the contrapositive of the first premise /meth -> /weed, woudln't the two negative meth components make a positive?