The actual area of the stadium is calculated by drawing a figure with a scale of 1:2000. The length of the stadium is 3.5cm and the width is 1.5cm

The actual area of the stadium is calculated by drawing a figure with a scale of 1:2000. The length of the stadium is 3.5cm and the width is 1.5cm

Super simple!
3.5 * 2000 = 7000 (CM)
1.5 * 2000 = 3000 (CM)
7000 △ 100 = 70 (m)
3000 △ 100 = 30 (m)
30 × 70 = 2100 (M2)