Answer:

57.5 m

Step-by-step explanation:

Perimeter of the rectangle

= 2(l+b)

= 2(75+40)

= 2×115

= 230 m

Therefore

the perimeter of square=perimeter of the rectangle

=> 4a = 230

=> a = 230/4

=> a = 57.5 m

let the side of square be x

according to the question

area of reactangle = area of square

75 × 40 m² = x²

3000m² = x²

x = √3000m²

x = √3 × √100 × ✓10 m²

x= √3 × 10 ×√10 m²

x= 10√30 m

hence the side of square is 10√30m