Hello,

to a.): You get the extreme value of A(x) if the first derivative of A equals zero.

Calculate A'(x).

Solve the equation A'(x) = 0 for x. (For confirmation only: x = 0 or x = 75)

to b.): Plug in the result from a.) into the given equation of the function. Determine which of the 2 values is the maximum (for confirmation only: )