Dax -- Dividing by aggregates from two different facts - powerbi

Question

I am trying to convert a piece of SQL to dax.
It only involves two tables, both facts and a common dimension attribute, Encounter.
I want to sum all charges by encounter and sum collections by encounter, filtered to only collections of TransactionRollup_Name = Contractual, TransactionTypeDescription = Adjustment, posted last month.
I will filter the System and Action <> Delete in the reporting client (powerbi or excel)
Once these are obtained I want the sum of contractual collections where the portion of contractual collections over total encounter charges is >= .9 and < 1
SQL:
DECLARE #startdate INT = 20181201
, #thrudate INT = 20181231
, #systemcode VARCHAR(1) = '1';
SELECT SUM(coll.Contractual)
FROM ( SELECT SUM(Amount) * -1 Contractual
, col.EncounterID
FROM
dwo.FactCollections col
JOIN dwo.DimTransactionCode_mds mds ON col.mds_TransactionID = mds.SK_TransactionKey
WHERE
mds.TransactionRollup_Name = 'Contractual'
AND mds.TransactionTypeDescription = 'Adjustment'
AND col.SystemID = TRY_CONVERT(INT, #systemcode)
AND col.Action <> 'Delete'
AND col.PostDateTime >= #startdate
AND col.PostDateTime <= #thrudate
GROUP BY col.EncounterID ) coll
JOIN ( SELECT EncounterID
, SUM(Amount) Charge
FROM dwo.FactCharges ldg
WHERE
ldg.SystemID = TRY_CONVERT(INT, #systemcode)
AND ldg.Action <> 'Delete'
GROUP BY ldg.EncounterID ) chg ON chg.EncounterID = coll.EncounterID
WHERE
chg.Charge <> 0
AND chg.Charge IS NOT NULL
AND coll.Contractual / chg.Charge >= .90
AND coll.Contractual / chg.Charge < 1.0;
Attempted Dax Measure:
90%-99.99% of Charges :=
CALCULATE (
'MeasureTable'[Sum of Contractual Adjustments],
FILTER (
'FactCollections',
DIVIDE (
'MeasureTable'[Sum of Contractual Adjustments],
'MeasureTable'[ChargeTotal]
)
>= .90
&& DIVIDE (
'MeasureTable'[Sum of Contractual Adjustments],
'MeasureTable'[ChargeTotal]
)
< 1.0
)
)
Charge := SUM ( 'FactCharges'[Amount] )
Sum of Contractual Adjustments :=
CALCULATE (
SUM ( FactCollections[Amount] ) * ( -1 ),
FILTER (
'Transaction Code',
'Transaction Code'[TransactionTypeDescription] = "Adjustment"
&& 'Transaction Code'[TransactionRollup_Name] = "Contractual"
)
)
Sample data on one encounter, per request.
Addendum
Going a different route with the dax, this gets me 1/2 way.
The summarizecolumns query gets me a result set that aggregates both charges and contractual collections up to the encounter and calculates the ratio of contractuals / charges.
The end result would need to filter this intermediate result set where
contractual / charge ratio is >= .9 and < 1
post dates for contractual collections should be filtered by reporting client filter context
All post dates for charges should be included, regardless of the post date filter context in the reporting client
I have no idea how to do that second part in dax though.
> EVALUATE SUMMARIZECOLUMNS (
> 'Encounter'[Encounter],
> "ChargeAmount", SUMX ( 'FactCharges', 'FactCharges'[Sum Charge Amount] ),
> "ContractualAmount", SUMX (
> 'FactCollections',
> CALCULATE (
> 'FactCollections'[Sum of Adjustments],
> 'Transaction Code'[TransactionRollup_Name] = "Contractual"
> )
> ),
> "Contractual : Charge", DIVIDE (
> SUMX (
> 'FactCollections',
> CALCULATE (
> 'FactCollections'[Sum of Adjustments] * -1,
> 'Transaction Code'[TransactionRollup_Name] = "Contractual"
> )
> ),
> SUMX ( 'FactCharges', 'FactCharges'[Sum Charge Amount] )
> ) )