$-$ Consider the network in the figure above where link speeds are shown in Mbps and answer the questions.

$($a$)(5$ points$)$ What is the minimum cost route from SOURCE to DESTINATION if all links have a cost equal to $1?$ List the routers in the optimal path in the correct order

$**$ Instruction $-$ Hops should be separated by a just a SPACE, do not add commas. Example answer: R$1$ R$3$ R$5$ R$7$

$($b$)(10$ points$)$ What is the minimum cost route if the cost of each link is defined as $100\backslash (\backslash$mathrm$\{$Mbps$\}/\backslash )($link speed$)$ i$.$e$.,$ a link with speed $40$ Mbps has a cost of $\backslash (100/40=2\mathrm{.}5\backslash ).$ List the routers in the optimal path in the correct order.

$\backslash (\{\}^\{**\}\backslash )$ Instruction $-$ Hops should be separated by a just a SPACE, do not add commas. Example answer: R$1$ R$3$ R$5$ R$7$