Mathgeometry
posted by Jen .
(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.

correct! this is called the contrapositive.
p>q ≡ ~q>~p
I will leave it to you to prove the identity with truth tables. 
Do it yourself.

a swimming pool is built as follow;
the top view is a rectangle 12ft by 30ft. the pool is 4 feet deep at the shallow end and 9 feet at the deep end. the sides walls are as shown. how many square ft of tile will it take to tile the two side walls and both end walls?