a) 12 kg + 23 kg = 35kg 45 kg + 20 kg = 65kg 9 kg + 7 kg = 16kg
b) 42 kg – 30 kg = 12kg 13 kg – 9 kg = 4kg 60 kg – 40 kg = 20kg
a) 12 kg + 23 kg = 35kg 45 kg + 20 kg = 65kg 9 kg + 7 kg = 16kg
b) 42 kg – 30 kg = 12kg 13 kg – 9 kg = 4kg 60 kg – 40 kg = 20kg