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## Homework Statement

a) p

b) ~q -> ~p

c) q -> r

d) (r V t)-> s

proves e) s

Use a demonstration to show the following argument form is valid

## Homework Equations

## The Attempt at a Solution

1) ~q-> ~p proves p -> q contrapositive

2) p-> q , p proves q modus ponens

3) q->r , q proves r modus ponens

This is where I get iffy and confused, I think this is allowed but want to verify

4) (r V t) -> s proves ~s -> ~(rVt) implication to disjuction

5) ~s -> ~(rVt) proves ~s->~r^~t DeMorgans

6) ~s -> ~r ^~t proves sV~r^~t by implication to disjunction

7) sV~r ^ ~t proves sV~r specialization

8) sV~r, r proves s

does this look legit if anyone has taken a discrete math course that has a sheet with this stuff :(?