Answer: The maximum = 3 tons
Step-by-step explanation:
The cost function C(x) = x + 5x + 7
P(×) = 13x - x^2 - 5x -7
If x <3
P= x^2 +8x -7
Differentiating to get x
dp/dx = -2x + 8
X= 8/2
C=4
Maximum will be 3 tons
When x=3
P= 13x - x^2 -5x +7 -3x + 9
When x>3
dp/dx = x^2+5x +2
X = 5/2 = 2.5