From the Venn diagram: 15 players like Chemstrand, 17 players like Chemgrass, 13 players like both Chemstrand and Chemgrass while 10 players like neither Chemstrand nor Chemgrass.
The missing values in the frequency table are x - representing the number of players that like both Chemstrand and Chemgrass, y - representing the number of players that like Chemgrass but do not like Chemstrand and z - representing the number of players likes Chemstrand but do not like Chemgrass.
The number of players that like both Chemstrand and Chemgrass is 13. The number of players that like Chemgrass but do not like Chemstrand is 17. The number of players likes Chemstrand but do not like Chemgrass is 15.
Therefore, x = 13, y = 17 and z = 15
        
                    
             
        
        
        
A vertex can be the max or min. The vertex is the highest point or lowest point of a function.
        
                    
             
        
        
        
Area of a triangle: A= 1/2(base)(hieght)
base=x
height= 6(base)+1= 6x+1
13= 1/2 × (x)(6x+1) 
(get rid of 1/2 by multiplying each side by 2)
26= (x)(6x+1)
26= (x × 6x)= 6x² (x × (+1))= x
26= 6x² + x
0= 6x²+x-26
Are either of those the answers? If not, list the options and I will be able to tell you which one is correct. Hope this helped!