1140. The windmill blades

    Pepe Chapuzas had drawn something like the blades of a windmill...

    The callenge was to calculate the sum of the blue angles... Chicho Madeja calculated it...

    Dear Teacher:

BLUE + RED = 5 · 180° = 900°
RED + GREEN = 360°
RED = GREEN
RED = 180°
BLUE = 900° − RED = 900° − 180° = 720°