Joe P. answered 11/24/19
Mathematical and Philosophical Logic Researcher and 5+ years tutoring
~ means "NOT"
The museum will be open only if it is not a holiday.
Translates to ~H --> O.
Assuming (as instructed) that H and O are each true, this conditional statement is true.
The truth table looks like
H O ~H --> O
T T T
T F T
F T T
F F F
You can get this more easily from the statement's equivalent form by (material implication) ~(~H) v O, which is equivalent to (by double negation) H v O.