Question 1029579
1. (R • J) ⊃ U----------------Hypothesis
2. (J • R) ⊃ U----------------Commutativity
3. J ⊃ ( R ⊃ U) --------------Exportation
4. J      ---------------------Hypothesis
5. R ⊃ U  --------------------Modus ponens on #3 and #4
6. ~(~R • ~N) -----------------Hypothesis
7. R v N ---------------------de Morgan's law and double negation
8. ~~R v N --------------------double negation
9. ~R ⊃ N  -------------------Material implication
10. ~N ⊃ R -------------------Contrapositive of #9
11. ~N ⊃ U  ------------------Hypothetical syllogism on #5 and # 10
12. ~~N v U ------------------Material implication
13.  N v U ---------------------Double negation
14. U v N  --------------------Commutativity