I don’t even know :( sorry
It is a line that divides the space into two.. The line is y=-x-3
Using the vertex of the quadratic function, it is found that:
a) The maximum number of customers in the store is at 12 P.M.
b) 75 customers are in the store at this time.
The number of customers in x hours after 7 AM is given by:

Which is a quadratic equation with coefficients 
Item a:
The maximum value, considering that a < 0, happens at:

Hence:

5 hours after 7 A.M, hence, the maximum number of customers in the store is at 12 P.M.
Item b:
The value is y(5), hence:

75 customers are in the store at this time.
A similar problem is given at brainly.com/question/24713268
Answer:
Step-by-step explanation:
-21-9k=-8(6k+3)
-21-9k= 48k+24
+9k +9k
-21=57k+24
-24 -24
-45=57k
divide 57 by -45
k= -1.2
idk if that helps, sorry