If/Then statements in Exact Form - Need Help

I am working on an exact form for a proposal.   I have numerous fields that if the "YES" is picked from the drop down field, I want a statement to go into the exact form proposal.

Such as         Field is:    Is Aggregate included:            possible answers in drop down are : YES   or   NO.  

How do I write it in the exact for that
if YES is selected then    " Aggregate to be supplied by Contractor " is put on the exact form

or 
if NO is selected then     "Aggregate supplied by Customer" is put on the exact form. 


Any help would be appreciated and Thanks in Advance!!!!

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Tina Revermann
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