How to Find Ui and Vj

For the routes used: U + V = cost of delivery
Let's find U i and V j step by step.
To do this, we need to enter the value of one of them. Let u2 = 0.
 Supplier Consumer U B 1 B 2 B 3 B 4 A 1 20 3 5 4 0 A 2 6 15 3 20 1 5 0 u2 = 0 A 3 10 3 20 2 7 0 V v2 = ?
A2B2 :   v2 + u2 = 3     v2 = 3 - 0 = 3
 Supplier Consumer U B 1 B 2 B 3 B 4 A 1 20 3 5 4 0 A 2 6 15 3 20 1 5 0 u2 = 0 A 3 10 3 20 2 7 0 V v2 = 3 v3 = ?
A2B3 :   v3 + u2 = 1     v3 = 1 - 0 = 1
 Supplier Consumer U B 1 B 2 B 3 B 4 A 1 20 3 5 4 0 A 2 6 15 3 20 1 5 0 u2 = 0 A 3 10 3 20 2 7 0 V v2 = 3 v3 = 1 v4 = ?
A2B4 :   v4 + u2 = 0     v4 = 0 - 0 = 0
 Supplier Consumer U B 1 B 2 B 3 B 4 A 1 20 3 5 4 0 A 2 6 15 3 20 1 5 0 u2 = 0 A 3 10 3 20 2 7 0 u3 = ? V v2 = 3 v3 = 1 v4 = 0
A3B2 :   v2 + u3 = 2     u3 = 2 - 3 = -1
 Supplier Consumer U B 1 B 2 B 3 B 4 A 1 20 3 5 4 0 A 2 6 15 3 20 1 5 0 u2 = 0 A 3 10 3 20 2 7 0 u3 = -1 V v1 = ? v2 = 3 v3 = 1 v4 = 0
A3B1 :   v1 + u3 = 3     v1 = 3 - (-1) = 4
 Supplier Consumer U B 1 B 2 B 3 B 4 A 1 20 3 5 4 0 u1 = ? A 2 6 15 3 20 1 5 0 u2 = 0 A 3 10 3 20 2 7 0 u3 = -1 V v1 = 4 v2 = 3 v3 = 1 v4 = 0
A1B1 :   v1 + u1 = 3     u1 = 3 - 4 = -1
 Supplier Consumer U B 1 B 2 B 3 B 4 A 1 20 3 5 4 0 u1 = -1 A 2 6 15 3 20 1 5 0 u2 = 0 A 3 10 3 20 2 7 0 u3 = -1 V v1 = 4 v2 = 3 v3 = 1 v4 = 0