Problem 1:
(d) Network has 10 links
(e) Node 1 has 2 incoming links and 2 outgoing links

Problem 2:
Topological order:
Node	Label
1	4
2	3
3	5
4	6
5	7
6	2
7	1

Problem 3
Network is not strongly connected; 2 is not reachable from 1

Problem 4
Minimum spanning tree:
(1,2)
(1,4)
(1,5)
(1,6)
(2,3)
(2,7)
Problem 5:
 Shortest path from 7 to 4 is
4 <- 3 <- 2 <- 6 <- 7