$$$- \frac{141 p t}{800} + \frac{1673}{500}$$$ 對 $$$t$$$ 的導數

和/差的導數等於導數的和/差：

$${\color{red}\left(\frac{d}{dt} \left(- \frac{141 p t}{800} + \frac{1673}{500}\right)\right)} = {\color{red}\left(- \frac{d}{dt} \left(\frac{141 p t}{800}\right) + \frac{d}{dt} \left(\frac{1673}{500}\right)\right)}$$

套用常數倍法則 $$$\frac{d}{dt} \left(c f{\left(t \right)}\right) = c \frac{d}{dt} \left(f{\left(t \right)}\right)$$$，使用 $$$c = \frac{141 p}{800}$$$ 與 $$$f{\left(t \right)} = t$$$：

$$- {\color{red}\left(\frac{d}{dt} \left(\frac{141 p t}{800}\right)\right)} + \frac{d}{dt} \left(\frac{1673}{500}\right) = - {\color{red}\left(\frac{141 p}{800} \frac{d}{dt} \left(t\right)\right)} + \frac{d}{dt} \left(\frac{1673}{500}\right)$$

套用冪次法則 $$$\frac{d}{dt} \left(t^{n}\right) = n t^{n - 1}$$$，取 $$$n = 1$$$，也就是 $$$\frac{d}{dt} \left(t\right) = 1$$$：

$$- \frac{141 p {\color{red}\left(\frac{d}{dt} \left(t\right)\right)}}{800} + \frac{d}{dt} \left(\frac{1673}{500}\right) = - \frac{141 p {\color{red}\left(1\right)}}{800} + \frac{d}{dt} \left(\frac{1673}{500}\right)$$

常數的導數為$$$0$$$：

$$- \frac{141 p}{800} + {\color{red}\left(\frac{d}{dt} \left(\frac{1673}{500}\right)\right)} = - \frac{141 p}{800} + {\color{red}\left(0\right)}$$

因此，$$$\frac{d}{dt} \left(- \frac{141 p t}{800} + \frac{1673}{500}\right) = - \frac{141 p}{800}$$$。