7. How many map sheets of size 1x1m require to plot a 20x20 km city using a scales of 1/500, 1/1000, 1/10000? 8. A square area of a land was measured on the ground, the length of one side was (500 m). What is the area in the unites (Donum, Olik, Hectare, Km)? 9. A land was plotted by an engineer on a map having scale (1:5000) and its dimensions 15 cm x 20 cm. What is the area on a ground in Hectare unit?