A knapsack should be filled to its maximum capacity. Number of products should be selected such that the total value is as high as possible, meanwhile not exceeding the maximum weight. 

assortment 1 4m €20
assortment 2 3m €14
assortment 3 2m €8

How should the tree cut into pieces, such that the total return w of the assorments is as high as possible?
 Maximise (w=20x1 + 14x2 + 8x3)
st. 4x1+3x2+2x3 <= 7
x1, x2, x3 >= 0 and integer valued

Also be stepwise decision problem.
Optimal cutting of the tree can be determined by finding the longest path through the network.