28. A rectangular lawn 60 metres by 40 metres have two road each 5 metres wide running in the middle of it one parallel to length and the other parallel to breadth. The cost of gravelling the roads at 60 paise per sq. metre is:

29. The ratio between the length and breadth of a rectangular field is 5:4, the breadth is 20 metres less than the length, the perimeter of the field is:

30. A rectangular plot is half as long again as it is broad. The area of the lawn is (2/3) hectares. The length of the plot is: