fix payment amount mismatch

app/models/sale.rb

@@ -1404,7 +1404,7 @@ def self.get_payment_method_by_shift(shift_sale_range,shift,from,to,payment_type
     if payment_type.present?
       sale_payment = sale_payment.where(payment_method: payment_type)
     end
-  
+
     return payments_total, sale_payment
 end
 
@@ -1438,10 +1438,10 @@ end
     cash = 0.0
     self.sale_payments.each do |pay|
         if pay.payment_method == 'cash'
-          cash = pay.payment_amount-self.amount_changed
+          cash += pay.payment_amount
         end
     end
-    return cash
+    return cash - self.amount_changed
   end
 
   def get_credit_amount