The method that is not correct is brandon's method.
Fifteen thousand, four hundred and nine
CD is congruent to XY, DA is congruent to YZ and AC is congruent to ZX even tho i'm not able to see properly your image
Je ne parle le Français très bonne, mais je te vais aider. Le total est 40kg et la valise pèse 20kg donc 40-20=20. La réponse est 20kg.