adding two absolute values arduino

Hi
I am trying to add two abs but I have an error, what is the solution ?

x = abs(fvin - fVo) + abs(Irms / 1000  - Vo, 3);

error: macro “abs” passed 2 arguments, but takes just 1
x = abs(fvin - fVo) + abs(Irms / 1000 - Vo, 3);

What is the 3 for? (not decimal places, check the reference)

The comma is a delimiter between arguments, that is why the compiler thinks there are 2 arguments to a 1 argument function.

Thanks
I removed 3 and it is OK