Create 3 Workflow Container Elements.
I_CURR: Current Quantity of Apples at shopping bag
I_USED: Quantity that client used apples.
I_REMAIN: Quantity of how many apples remains at client’s shopping bag.
Create container element ‘I_CURR’

Set Import Parameter and Mandatory ‘X’.

Do the same operation for I_USED
Set Import Parameter and Mandatory ‘X’.
Create container element I_REMAIN .

Mark Export parameter ‘X’

Create ‘Container Operation’

Fill your expression fields like in the following screen

