The purpose of an expert system is to capture best practice solutions and program them into a set of rules in a software program. Expert systems are computers that use artificial intelligence technologies to simulate a behavior of a human or another subject. 
The knowledge about a specific subject is transformed with this system into a software code. 
        
             
        
        
        
Oh a document, I do not believe that you have type on images, but if you were to type a text in a app called PicsArt and saved it and then put it onto the document over the picture it would work.
        
                    
             
        
        
        
I am not sure what you mean by that but a boolean is either true or false. So it is kind of like a true or false question. 4+4=7 is false. 2*4!=48 is true.
        
             
        
        
        
Answer:
The answer is consistency
Explanation:
Information systems deal with the retrieval, storage, manipulation and sharing of data for organisational needs. It is important that there are measures in place that corresponds to data validity standards. The process that ensures that operations meet these standards is known as consistency.
This is very necessary for information systems.
 
        
             
        
        
        
Answer and Explanation:
For returning four columns from the  Invoices table, named Number, Total, Credits, and Balance the SELECt statement is as follows
Select     Invoice Number     As     Number
               Invoice Total          As      Total
Payment total + credit total  As      Credits
Invoice total 
(Payment total + credit total) As     Balance
These are displayed as above