Form Calculations off

I have a form that calculates values from two fields and populates a third with the result. But the result is not correct?

Screen Shot 2020-01-28 at 11.40.24 AM1618×604 50.1 KB

Here is my expression

dmx-bind:value="inputAddTransactionGross.value.toNumber() - inputAddTransactionTaxes.value.toNumber()"