LiveCycle ES2 Calculated Field No Greater Than a Certain Value

Good day y'all,

I'm a bit lost. I'm using ES2 for work stuff (it's the government and it's what I got). There is a field that I need to get to mirror the amount of another field but no greater than a certain authorized amount.

Essentially, I have a field (Subsidy Amount) that needs to reflect the amount another field (Total Monthly), but no more than $100 (that's an example figure). I'm trying different rules, but it either doesn't fill in, or it goes over the authorized amount. I cannot make the "Subsidy Amount" read-only as it may need to be changed by someone else in the chain if a lower than calculated amount is approved.