If a person is 18 years old, then the person can vote in the presidential election. linda cannot vote; therefore, linda is not 18 years old.

determine if the statement is valid.

a.
no, p → q, therefore, q → p is an invalid argument.
b.
no, p → q, therefore, ~q → ~p is an invalid argument.
c.
yes, p → q, therefore, ~q → ~p is a valid argument.
d.
there is not enough information to determine.