Anyone know what the answer would be?

That is correct 8.25 multiplied by 7 is 57.75

3.) 100.5 cubic feet

The second statement is incorrect. the third statement is also incorrect, there is no such thing as a negative zero. the last statement is also incorrect because what your saying is that negative 49 is the opposite of negative 49 which is false because the opposite of negative 49 is positive 49.