4. A construction company has three teams of workers available, each of which is to be assigned to one of four jobs at a site. The following table shows the estimated cost, in tens of pounds, of each team doing each job:
| Windows | Conservatory | Doors | Greenhouse |
| Team A | 27 | 80 | 8 | 81 |
| Team B | 28 | 60 | 5 | 71 |
| Team C | 30 | 90 | 7 | 73 |
Use the Hungarian algorithm to find an allocation of jobs which will minimise the total cost. Show the state of the table after each stage in the algorithm and state the cost of the final assignment.