How to do a subtraction from col a to col b

[Beto16]

Hi I have a table that looks like this
Id. DollarA. Dollar B
1. 10. 45
2. 50. 35
3. 20. 25
I need it to look like this
. DollarA. Dollar B. DIFF
1. 10. 45. 35
2. 50. 35. 15
3. 20. 25. 5

Thanks for assistance

[Reeza]

Diff = b - a;

[jklaverstijn · Accepted solution]

Looks like you need the absolute value of the difference:

diff=abs(a-b);

- Jan.

[Beto16]

Thank you -Jan