a) 40 kg + 20 kg = 60 kg
60 kg - 40 kg = 20 kg
8 kg + 5 kg = 13 kg
13 kg - 8 kg =5 kg
25 kg + 31 kg = 56 kg
56 kg - 31 kg = 25 kg
b) 30 l + 10 l = 40 l
40 l - 10 l = 30 l
7 l + 6 l = 13 l
13 l - 7 l = 6 l
45 l + 23 l = 68 l
68 l - 23 l = 45 l
a) 40 kg + 20 kg = 60 kg 8 kg + 5 kg = 13 kg 25 kg + 31 kg = 56 kg
60 kg - 40 kg = 20 kg 13 kg - 8 kg = 5 kg 56 kg - 31 kg = 25 kg
b) 30 l + 10 l = 49 l 7 l + 6 l = 13 l 45 l + 23 l = 68 l
40 l - 10 l = 30 l 13 l - 7 l = 6 l 68 l - 23 l = 45 l