Hi,
In addition to Stefan's suggestion, you can bookmark the original amount
due and the discount rate and use the bookmarks in the formula field.
For example, in the following sentence select 100 and create a bookmark
called AmountDue, and select 25 and create a bookmark called
DiscountRate.
You owe $200, but with a 25% discount you would need to pay only $.
Then after the the last dollar sign ($), add the following field codes.
{={ AmountDue } - { AmountDue }*{ DisountRate }/100}
As Stefan mentioned, to create each pair of field delimeters, do not type
the curly brackets. Instead, select what they will enclose and press
Ctrl+F9. After you finish creating the field codes, press F9 and then
press Alt+F9. The number 150 should appear.