Area of square = 5 x 5 = 25

Area of triangle that is half the rectangle = (11 x 8)/2 = 44

Area of triangle unshaded on bottom-right = (1/2)(11+5) x 5 = 40

Therefore, area of shaded part = 25+44-40 = 29 cm²

Thank you so much, Sushi88!

Most welcome! 🙂

Area of top unshaded triangle = (8*11)/2 = 44
Area of bottom unshaded triangle = ((11+5) * 5)/2 = 40
Area of top notch at the top = 5*3 = 15
Area of whole rectangle = 8*(11+5) = 128

Area of shaded parts = 128 – 44 – 40 – 15 = 29cm² #

Thank you ChiefKiasu!