Still not getting the answer. My teacher teaches us as if we were algebra dummies or something like that, so probably he explained to us in a very complicated way, thinking that we got it?

$\displaystyle \frac{dr}{dt} = ?$

$\displaystyle \frac{ds}{dt} = \frac{25ft}{s}$

$\displaystyle r = \sqrt{300^2+s^2}$

$\displaystyle = \sqrt{340000}$

$\displaystyle tan\theta=\frac{s}{300}$

$\displaystyle (sec^2\theta)(\frac{d\theta}{dt}) = \frac{1}{300} (\frac{ds}{dt})$

$\displaystyle \frac{d\theta}{dt} = \frac{1}{12}(cos^2\theta)$

$\displaystyle \frac{d\theta}{dt} = \frac{25}{408}$

$\displaystyle csc\theta = \frac{r}{300}$

$\displaystyle -csc\theta cot\theta (\frac{d\theta}{dt}) = \frac{1}{300} (\frac{dr}{dt})$

$\displaystyle \frac{-sqrt{340000}}{12} (\frac{5x100}{408} = \frac{dr}{dt}$

$\displaystyle \frac{dr}{dt} = -59.54811...$

$\displaystyle csc\theta = \frac{r}{300}$

$\displaystyle -csc\theta(cot\theta) (\frac{d\theta}{dt}) = \frac{1}{300} (\frac{dr}{dt})$

$\displaystyle \frac{-\sqrt{340000}}{12} (\frac{500}{408}) = \frac{dr}{dt}$

$\displaystyle \frac{dr}{dt} = -59.54811...$

Still not getting the answer