If you are working with time or days, you can't put in a negative value because if you are doing an experiment, you can't go back in time to do that experiment to gather data. (Time for the most part considered to be an input value so that's why I used it as an example.)
The answer is 52.80 because the tip is $8.80 and 44.00+8.80=52.80
The answer is -1 over 512 (fraction form)
ANSWER: -1/512