please help------------,

Answer:
600 cm²
Step-by-step explanation:
The shaded area (A) is calculated as
A = area of square - ( area of 3 unshaded triangles )
area of square = 40 × 40 = 1600 cm²
area of lower right triangle = [tex]\frac{1}{2}[/tex] × 20 × 40 = 10 × 40 = 400 cm²
area of upper left triangle = [tex]\frac{1}{2}[/tex] × 40 × 20 = 20 × 20 = 400 cm²
area of lower left triangle = [tex]\frac{1}{2}[/tex] × 20 × 20 = 10 × 20 = 200 cm²
Then
A = 1600 - (400 + 400 + 200 ) = 1600 - 1000 = 600 cm²