Tính: a) 4 × 5 4 × 6 4 × 9 20 : 4 24 : 4 36 : 4 20 : 5

a)

4 × 5 = 20                        4 × 6 = 24                        4 × 9 = 46

20 : 4 = 5                         24 : 4 = 6                         36 : 4 = 9

20 : 5 = 4                         24 : 6 = 4                         36 : 9 = 4

b)

12 kg : 4 = 3 kg

28 mm : 4 = 7 mm

40 l : 4 = 10 l