In the following partial proof what is the justification for

In the following partial proof, what is the justification for line 9 ?

1.     (R H) • (S I)

2.     (H • L) (R S)

3.     H • (K T)

4.     H L / I M

5.     H                  3 Simp

6.     L                  4, 5 DS

7.     H • L            5, 6 Conj

8.     R S            2, 7 MP

9.     H I            _______

1, 8 CD

9, Simp

1, 8 MP

9, 5 DS

There is no justification; line 9 is a mistake.

Solution

option c . that is 1, 8 MP