Let i, s, c, p , e be the following propositions: i = "There is ice" s= " There is snow" c = "School is closed" p = "Practice exam is canceled" e = "Exam is postponed" Consider the following argument: If there is ice or snow, then school will be closed and practice will be canceled. If school is closed, then exams will be postponed. Exams were not postponed. a) [5 pts] Convert the argument into logical notations using the variables i,s,c,p and e. b) [15 pts] Did it snow? Formally prove your answer using the techniques and rules in logic. Justify each step in your proof by a rule from propositional calculus and mention the name of each rule you use. Don't add any assumption to the argument