Salut

1 m = 100 cm

50 cm = 100 cm ÷ 2

donc : 50 cm = 1/2 × 100 cm = 1/2 × 1 m

1 m = 10 dm

donc 2 dm = 2/10 m = 1/5 m

1 m = 1 000 mm = 100 × 10 mm

donc 10 mm = 1/100 m

1 m = 10 dm

donc 14 dm = 14/10 m = 7/5 m