Question 1078152
Look at each node (circle).
Flow in is positive, flow out is negative.
The sum of the flows into a node equals zero.
I'll do one, you do the rest.
Look at the upper left node,
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*[illustration PS6.JPG].
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So summing the flow for that node,
{{{300-x[1]-x[2]=0}}}
{{{x[1]+x[2]=300}}}
Do the same for the other nodes.