Vous pouvez m'aider svp :( ?? 5ème

bonsoir

3/4 m = 0.75 m = 7500 mm
4/5 dam = 0.8 dam = 80 dm
3/8 km = 0.375 km = 3750 m 
2/5 hm = 0.4 hm = 40 m
1/2 x 1/10 hm = 1/20 hm = 0.05 hm = 5 m
1/2 x 1/4 dm = 1/8 dm = 0.125 dm = 1.25 cm
1/2  x 1/5 dam = 1/10 dam = 0.1 dam = 10 dm
1/2 x 1/4 km = 1/8 km = 0.125 km = 1250 m

3/4 m = 0,75 m = 750 mm
4/5 dam = 0,8 dam = 80 dm
3/8 km = 0,375 km = 375 m
2/5 hm = 0,4 hm = 40 m

1/2 x 1/10 hm = 1/20 hm = 5 m
1/2 x 1/4 dm = 1/8 dm = 0,125 dm = 1,25 cm
1/2 x 1/5 dam = 1/10 dam = 0,1 dam = 10 dm
1/2 x 1/4 km = 1/8 km = 0,125 km = 125 m