Math
posted by Jen on .
(a) translate the argument into symbolic form and (b) determine if the argument is valid or invalid. You may compare the argument to a standard form or use a truth table.
If Nicholas Thompson teaches this course, then I will get a passing grade.
I did not get a passing grade.
∴ Nicholas Thompson did not teach the course.

If a cow, then mammal  hypothesis
If a mammal then a cow  converse, invalid
If not a cow , then not a mammal  inverse, invalid
If not a mammal, then not a cow  contrapositive  true
Here:
If NT teaches, then pass  hypothesis
If pass, then NT  converse, invalid
If not NT, then not pass  inverse, invalid
If not pass, then not NT  contrapositive, true (this is your case) 
(a) translate the argument into symbolic form and (b) determine if the argument is valid or invalid. You may compare the argument to a standard form or use a truth table.
If I can get my child to preschool by 9:45AM, then I can take the 9:00AM class.
If I can take the 9AM class, then I can be done by 2PM
If I can get my child to preschool by 8:45AM then I can be done by 2PM