Answer
$\frac{∂w}{∂ℎ}$ pounds per inch
Work Step by Step
It is given that $w(a, h)$ is the weight of a person where $a$ is their age, and $h$ is their height in inches. The rate of change of weight with respect to height is therefore $\frac{∂w}{∂ℎ}$ pounds per inches (we do not consider $a$ so it is a partial derivative).
