Answer:
System of linear equations is solved below and explained in detail.
Explanation:
Part a: 
M = [1  3  5  2; 2  -4  7  -3; 0  -4  -7  3; 5  -3  2  1];
c =  [7;  -3;  -1;  0];
Part b:
The statement used for the solution of system of linear equation will be:
X = linsolve(M,c)
where X will give the values of x1, x2, x3, x4 respectively.
Part c:
The system is solved in matlab using above equation and the results are attached in a file.
The values for X are:
x1 = -2/7
x2 = 3/7
x3 = 4/7
x4 = 11/7
 
        
             
        
        
        
Answer:
Cover letter 
Explanation:
The type of business letter Melissa and Melrose would need to write is a Cover letter.
The Cover Letter is usually not more than a page document which gives a kind of summary or hint about who individual is and the quality of the individual, while highlighting why an individual is the best fit for the role they are seeking for.
Most recruiters usually make use of the cover letter, as a first hurdle, to screen out applicants especially when applications are much.
Melissa and Melrose, in addition to the resume they would submit for the volunteering job, would need a cover letter.
 
        
                    
             
        
        
        
I guess the word in the blank is Standardization.
Human systems integration (HSI), a supportability issue that every program should consider, addresses such factors as accessibility, visibility, testability, and Standardization.