Check Boxes combined with IF functions

I have a section of a form that requires you to check "RateComparison" or "MultiLocation". Depending on which box is checked, the "Lodging" line will be filled.

Here is the written version of my goal:

If "RateComparision" is checked, then "Lodging" is equal to the lowest value of "TripTotal1", "TripTotal2", and "TripTotal3".

If "MultiLocation" is checked, then the "Lodging" is equal to "GrandTotal".

And... here is the nightmare of a code I've created. *Note: RateComparison and MultiLocation are both under CheckBox "Group1"

var a = this.getField("TripTotal1").value;

var b = this.getField("TripTotal2").value;

var c = this.getField("TripTotal3").value;

var d = this.getField("CheckOne").value;

var e = Math.min(a, b, c);

if (d === "On" && this.getField("TotalTrips") > 0) {this.getField("TotalBacktoTravelRequest").value = e; }

if (d === "Off" && this.getField("TotalTrips") > 0) {this.getField("TotalBacktoTravelRequest").value = this.getField("TotalTrips").value; }

if (this.getField("TotalTrips").value === 0) {this.getField("TotalBacktoTravelRequest").value = 0; }

Thanks for any help!