Suppose the path from A to B has a single switch S in between: A$$S$$B$.$ Each link has a propagation delay of $60$sec and a bandwidth of $2$ bytes$/$sec$.$

$($a$).$ How long would it take to send a single $600-$byte packet from A to B$?$

$($b$).$ How long would it take to send two back$-$to$-$back $300-$byte packets from A to B$?$

$($c$).$ How long would it take to send three back$-$to$-$back $200-$byte packets from A to B$?$