For the Problems Below, Find: A) $\Delta \mathrm{s}$ And B) $\overline{\mathrm{v}}$ For Each Function Expressing Distance

For the problems below, find: a) $\Delta \mathrm{s}$ and b) $\overline{\mathrm{v}}$ for each function expressing distance $\mathrm{s}$ in terms of time $\mathrm{t}$ . 21) $s=5 t+3$
-Given $s=f(t)=4 t^{2}$ - 9, find the instantaneous velocity $v$ of an object moving along a straight line when $t=3$ . The distance, $s$ , is in metres and $t$ is in seconds.