solve for w$,$r$,$s$,$t

The Mosteller formula for approximating the surface area, $S,$ in $m^2,$ of a human is given by $S=\frac{\sqrt[\phantom{2}]{h}w}{60},$ where h is the person's height in cm and w is the person's weight in kg $.$ Complete parts $a),b),$ and $c)$ below.

a$)$ Compute $\frac{\text{d}\text{e}\text{l}\text{S}}{\text{d}\text{e}\text{l}\text{h}}.$

$\frac{\text{d}\text{e}\text{l}\text{S}}{\text{d}\text{e}\text{l}(h)}=$

$$

b$)$ Compute $\frac{\text{d}\text{e}\text{l}\text{S}}{\text{d}\text{e}\text{l}\text{w}}.$

$\frac{\text{d}\text{e}\text{l}\text{S}}{\text{d}\text{e}\text{l}\text{w}}=$

$$

c$)$ The change in $S$ due to a change in $w$ when $h$ is constant is approximately $S$~~$\frac{\text{d}\text{e}\text{l}\text{S}}{\text{d}\text{e}\text{l}\text{w}}w.$ Use this formula to approximate the change in someone's surface area given that the person is $150$ cm tall, weighs $73$ kg $,$ and loses $4$ kg $.$ The change in surface area is approximately $m^2.($Round to four decimal places as needed.$)$