Building further on the suggesting of Andrej Gajdunk using abs. I think what you want is to create a new Rule where you do the comparison. Than add in your microflow a new decision where you’d like the rule to be used.
The input is here the min and max saldo:
If you want to go different path’s after the check you can use for example a Validation feedback and a merger after or just stop the flow. If you want to do more than one check to see if your flow is valid, you can add a new bool variable at the beginning of your microflow. And set it on false whenever it fails a check. . For example like this:
Offcourse you could do it simply by adding one decision in your microflow without using a new rule. The rule is just handy when you want to reuse the same check multiple times.
There are several approaches you can take.
First, you could use abs to convert the negative number to a positive https://docs.mendix.com/refguide/mathematical-function-calls#9-abs
Second, you could turn both numbers into strings then remove the minus sign and compare them like that
substring($NegativeNumber+’’,1) = $PositiveNumber+’’
Hope this helps