Answer:
72 × 3 = 216m
216 m is the combined length
You would have to add a positive 6 to the negative 6 to get zero. Lets say you have -2 in order to get it to zero or just any positive number, you have to add a positive of the same value or higher to be able to get it there. I hope you understand that.
Domain is x’s and range is y’s.
For a, the domain is -2<=x<1
For a, the range is 1<=y<2
For b, the domain is 1<=x<=2
For b, the range is -2<=y<=2
(The <= is the ones with a line under, meaning equal to, if that makes sense. So write with a line under rather than equal sign)
Hope this helps!