Use a contrapositive proof to prove the following argument O

Use a contrapositive proof to prove the following argument: Only a fool would lie about one of Elaine\'s sorority sisters to her. A classmate of Elaine\'s lied about Joanne to her. Therefore, if none of Elaine\'s classmates are fools, then Joanne is not a sorority sister of Elaine. (F(x) = x is a fool; L(x,y,z) = x lies about y to z ; C(x,y) = x is a classmate of y; S(x,y) = x is a sorority sister of y; e = Elaine ; j = Joanne)

Solution

generally

\"If P, Then Q\".

then

so Joanine is a sorority sister of Elaine and one of the Elaines class mate is fool

then the conclusion is that Elaine\'s classmate didn\'t lie about joanne to her