Using the following instructions, form the transportation tableau corresponding to the following transshipment problem, where the availability at nodes $1,2,$ and $3$ are respectively $10,20,$ and $25,$ and the requirement at nodes $5,6,$ and $7$ are respectively $10,25,$ and $10.$

a$)$ Determine the Supply, Demand and Transshipment points. Points supply capacities and demand requirements. $(10$ pts$)$

b$)$ Construct a balanced transportation tableau. $(10$ pts$)$