$1)$ Use Figure $1$ as a reference, if the values $$are A$,$ B$,$ C and D $($in the $3$rd octet$)$ with the following conditions:

Grade A $=$ the sum of the last $5$ digits of your NIM$($so i will be $77404)$

Grade B$=$ A $+3$

Grade C$=$B $+5$

Grade D$=$C $+7$

$$ D$1,$ E$1,$ F$1$ are interfaces for the gateway router, while D$2,$ D$3,$ E$2,$ E$3,$ F$2,$ F$3$ are interfaces for the router

a$.$ How many networks $($LANs$)$ are there in the picture?

b$.$ Determine the Routing Table for R$1,$ R$2,$ and R$3$ using the following table!

c$.$ Using the Routing Table that you have specified in point b$,$ write down which path the ICMP packets $($Echo and Echo reply$)$ will take if you run the PING command from PC$1$ to PC$4$ and from PC$1$ to PC$6$