This is a standard mathematical calculation. I am giving four different possible scenario here.
| Example 1 | result = 1 | =(5)-(4) |
| Example 2 | result = 9 | =(5)-(-4) |
| Example 3 | result = -9 | =(-5)-(4) |
| Example 4 | result = -1 | =(-5)-(-4) |
So i would suggest you as per business requirement you have to control the sign of both the variables.
