Equation $d_{\text{e}\text{n}\text{d}-to-\text{e}\text{n}\text{d}}=N*\frac{L}{R}($Equation $1\mathrm{.}1$ in textbook$)$ gives a formula for the end$-$to$-$end delay of sending

one packet of length $L$ over $N$ links of transmission rate R$.$ Generalize this formula for sending $P$ such

packets back$-$to$-$back over the $N$ links.