1) 1hour, 20minutes=80minutes

2 hours=120 minutes

80/120= 2/3

2) 4 weeks = 28 days

49 days

28/49= 4/7

3) 3 years 4 months = 40 months

5 years 5 months = 65 months

40/65=8/13

4) 2m 40 cm = 240 cm

1 m 44 cm = 144cm

240/144=5/3

5) 5kg 500g = 5500g

2kg 750g = 2750g

5500/2750 = 2/1