(x – 15)(x – 6) = (x – 4)(x – 16)

x² – 6x – 15x + 90 = x² – 16x – 4x + 64

–21x + 90 = –20x + 64

–21x + 20x = 64 – 90

–x = –26      / : (–1)

x = 26    

Wymiary prostokąta:

x – 15 = 26 – 15 = 11          oraz        x – 6 =