Answer:
mud bricks for trading water channels for trading ships
Explanation:
 
        
                    
             
        
        
        
Answer:
Problem recognition
Explanation:
Problem recognition is related to the decision making to differentiate between the desired state and the actual state of the objects. It will activate the decision-making process. Motivation plays a vital role in the recognition of the problem. It play with two factors such as:
- What is the importance of the problem ?
- What is the magnitude of the discrepancy between the actual state and the desired state?
There would be a situation exist that clarifies the recognition of the problem but there many vague definitions that confused.  
Thus in the above statement, Jeff used the problem recognition strategy through which Jeff recognize the problem. 
 
        
             
        
        
        
I believe the answer is: Empirical
Empirical method refers to a method to obtain a certain knowledge that is initiated by using objective measurements, experiments, and observations.
From all method of studies, empirical method is the one that deemed as the least biased/more trustworthy.
        
             
        
        
        
Ans: 14x^4 - 18x^3 + 43x^2 + 24x -15
Explanation:
Given:
(7x+5)(2x^3-4x^2+9x-3)
7x(2x^3-4x^2+9x-3) + 5(2x^3-4x^2+9x-3)
14x^4 - 28x^3 + 63x^2 - 21x + 10x^3 - 20x^2 + 45x - 15
Hence,
14x^4 - 18x^3 + 43x^2 + 24x -15
-i