(a) Differentiate $A(m, h)$ with respect to $m$ to find $A_{m}(m, h)$.
\[
A_{m}(m, h)=\frac{\partial}{\partial m}\left(0.024265 h^{0.3964} m^{0.5378}\right)=
\]
(Round to five decimal places as needed.)

Step 1 ：Differentiate the function $A(m, h) = 0.024265 h^{0.3964} m^{0.5378}$ with respect to $m$ using the power rule for differentiation.

Step 2 ：The power rule states that the derivative of $x^n$ with respect to $x$ is $n*x^{n-1}$.

Step 3 ：In this case, we need to differentiate $0.024265*h^{0.3964}*m^{0.5378}$ with respect to $m$.

Step 4 ：The derivative of a product of functions is given by the product rule, which states that the derivative of $f(x)*g(x)$ is $f'(x)*g(x) + f(x)*g'(x)$.

Step 5 ：Here, $f(m) = m^{0.5378}$ and $g(m) = 0.024265*h^{0.3964}$. So, we need to find $f'(m)$ and $g'(m)$ and then use the product rule to find the derivative of the function.

Step 6 ：The derivative of $A(m, h)$ with respect to $m$ is $A_{m}(m, h)=0.013049717 h^{0.3964} m^{-0.4622}$.

Step 7 ：\(\boxed{A_{m}(m, h)=0.013049717 h^{0.3964} m^{-0.4622}}\)