Discrete Math

I'm confused with the questions listed below. Can you please solve and explain in detail? how it transforms one to the other to get the answer?

Using propositional logic properties and other logical equivalences (not truth tables), prove the following statements: 1. (p Vq) V (p V -q) is a tautology 2. ((p-+ r) (q r) (pv q)) _+ r is a tautology 3. (pVq) (- q) is a contradiction 4. (1-p) (p qAs . r) p is a contradiction