Answer:
pairs
Step-by-step explanation:
Given
Profit on selling 'x' pairs of shoes is 
Find the derivative of the function to find out the critical points

Thus, for 4 pair of shoes profit is maximize.
Answer:
8
Step-by-step explanation:
The midpoint of AC is ...
B = (A +C)/2 = (-10 +14)/2 = 2
The midpoint of BC is ...
D = (B +C)/2 = (2 +14)/2 = 8
The midpoint of BC is 8.
-0.5,-0.4,-0.3,-0.1,0,1,2,3,4,4.17