23
-13
To 3 decimal places the numbers are about -1.576 and -11.424 but it's quite possible to find exact their exact values by using the quadratic equation formula
Positive 13 does not equal to negative 13 because the positive 13 is greater than negative 13.
-13-(-50)= -13+50= 37
55
Nothing
0
13
-35
49
4 and 9
-113
23
55
98
13