1ère balance :
On met tout en gramme : 1 hg = 100g
2 hg = 200g
20g + 10g + confiture = 200g
confiture + 30g = 200g
confiture = 200 - 30
confiture = 170g
Le poids de la confiture est donc de 170 grammes
2. Confiture + 10g = 2hg + 2hg + 50g
Confiture + 10g = 200g + 200g + 50g
Confiture + 10g = 450g
Confiture = 450 - 10
Confiture = 440g
Le poids de la confiture est donc de 440 grammes
