constant term in any function is the term whose value does not change on variation of other parameters or in other case. We can also say constant term is independent of variable parameters. 
take example 
y = x + 3
here 3 is constant term which will not change either I change x or y . 3 is independent . it's just helps equation to hold information that overall in equation its matter. 
so in given problem -4 is the constant
 
        
             
        
        
        
Answer:
The answer is (18,15)
Step-by-step explanation:
Sorry if you get this wrong tho :/
 
        
             
        
        
        
I am thinking it would be 6
        
             
        
        
        
17k - 6k- 5k - 2k - k = 15
17k - 6k is 11k.
so, 11k - 5k - 2k - k =15
11k-5k is 6k
so 6k - 2k - k
6k - 2k is 4k
so 4k - k
4k - k is 3k
so 3k = 15
Take 3 to the other side --   k= 15/3
final answer is k = 5