I think this is the graph for your answer, for the next question like this, try to use "Desmos"
 
        
        
        
Since the ratio of sides is 4 to 3, the proportion is:

x = 
9
 
        
        
        
Answer:
$6.10
Step-by-step explanation:
Given the fabric store sells the fabric for $6.97 per yard
Given that a customer buys 7/8 yard of fabric.
Let the cost the customer pays be x then 

 
on cross multiplication we get

x=6.01 
Therefore the amount the customer should pay is $6.01