I am not quite sure, but the $-sign expansion should help you.
For ex. :
output_a= Count( $(variable_a) ) or
output_a= Count( $(=variable_a) )
For further details please see help
For testing purpose or getting started you can edit some easy expressions in a textbox and see what's happening.
I hope I understand you right what you are trying to achieve.
To give you an example
Let say you have 2 variables :
eIncomeExl = sum(AmountExcl)
eDedutionsExl = sum((Deductions) * (-1)) /114 * 100
Then I create another variable:
eSales = $(eIncomeExl) - $(eDedutionsExl)
Then in my Qlikview expression I would want the sales I use =$(eSales)
or if you just need the income in the expression you can just use use =$(eIncomeExl)