Answer:
Option C 
Step-by-step explanation:
Let
x ----> the cost of the concert ticket
we know that
The total cost to be no more than $4 Above  $80
so

Solve for x

The total cost to be no more than $4  below $80
so

Solve for x


therefore
The inequality that represent this problem is

<u><em>Verify</em></u>
<em>First solution (positive case</em>)


Solve for x
 ----> is ok
 ----> is ok
<em>Second solution (negative case)</em>

Multiply by -1 both sides


Solve for x

 ---> is ok
 ---> is ok
Remember that
 is equivalent to
 is equivalent to 
Because is a absolute value
 
        
             
        
        
        
Answer:C. competitive firms' profits are zero.
Step-by-step explanation: Perfect competition is the highest level of competition where the number of buyers and sellers are large,all firms are price takers,no government intervention,the products are homogeneous,no firm makes extraordinary profits, there is free entry and exit for buyers and sellers etc.
IN THE LONG RUN A PERFECTLY COMPETITIVE FIRM MAKES ZERO PROFITS.
 
        
             
        
        
        
Bc that’s not the right strategy to use it