Answer:
to square a number you multiply the number by itself.
a positive number times a positive number is a positive number.
a negative number times a negative number is a negative number.
and if you are multiplying 2 numbers with the same sign they will always be a positive number.
Take how much was added, divide by how much you originally had. 100-80=20. 20/80= 25%
The third option is ordered least to greatest