How Can I Sum Cell Value (Formated as Text) Separated by Delimiter “+” I have Tried with This Formula but its showing Error

The ‘SUM’ function requires a list of numeric inputs

Here Is My Formula

IF(AND([Material]=“BOPP”,[Unit]=“Pcs.”),(SUM(SPLIT([Width],"+"))*SUM(SPLIT([Length],"+"))*[Gauge]) /880*[Order Pending Qty.]/1000)

Hill to Solve This Issue