7. A hall 20 m long and 15 m broad is surrounded by a verandah of uniform width of 2.5 m. the cost of flooring the verandah at the rate of Rs. 3.50 per sq. metre is:

8. The cost of cultivating a square field at the rate of Rs. 160 per hectare is Rs. 1440. The cost of putting a fence around it at 75 paise per metre is:

9. The length of hall is 4/3) times its breadth. If the area of the hall be 300 square metres the difference between the length and the breadth is: