As it is presented in the passage, the approach to history taken by mainstream U.S. historians of the late nineteenth...

Skylar on July 19, 2020

@Daniellelagos, happy to help!

No, M does not have to be 3rd just because L is 6th.

Rule #1 tells us:
M(3) -> L(6)
not L(6) -> not M(3)

We can only make deductions when we have the sufficient condition present, which is M(3) in our original statement and not L(6) in our contrapositive. Notice that L(6) is never the sufficient condition, so we cannot assume what will happen if L is 6th. Perhaps M is 3rd, perhaps it isn't, we don't have enough information to say either way.

However, O>L is the sufficient condition of the contrapositive of Rule #2, so we can make a deduction here. When O precedes L (which must be the case here since L is last), Z cannot be first. In other words, at least one food must be added before Z.

Does that make sense? Please let us know if you have any other questions!