a) Network diagram showing the objective and flow constraints is as follows
In the below network diagram, cost is shown with Red numbers on the arrow. Flow constraint (capacity) is shown with Black numbers. Netflow constraint on each node is shown with Blue numbers next to each node.
b) Solution of the problem is as follows
Formulae used in the above model, G2 =SUMPRODUCT(B2:F2,$B$13:$F$13) copy to G2:G11
X13 = 2, X34 = 1, X24 = 2, X32 = 1, X21 = 0
Objective = 15