Răspuns :
1 km²=1.000.000 m²
0,0004 km² = 400 m²
5x - 3* 400 m² = 200m²
5x - 1200 m² = 200m²
5x = 1400 m²
x = 280 m²
0,0004 km² = 400 m²
5x - 3* 400 m² = 200m²
5x - 1200 m² = 200m²
5x = 1400 m²
x = 280 m²
5X- 3× 400m^2= 200m^2. rez ca 5X - 1200m^2 = 200m^2. rez ca 5X = 200+1200 rez ca 5X= 1400 m^2 X= 1400: 5 rez ca X= 280 m^2