The voltage across and current through a certain device are given by

vt$=1001-$exp$-0\mathrm{.}2$tV

$$

it$=30$exp$-0\mathrm{.}2$tmA

$$

a$)$ Find the instantaneous power p$($t$)$ at$$ t $=0$ and t $=3$ s

b$)$ Find the cumulative energy delivered to the device from t $=0$ to t $=$ oo