Bonjour,
Ex. 30 :
a) 3/4 de 32 = 32 × 3/4 = (32×3)/4 = (4×8×3)/4 = 8×3 = 24
b) 2/3 de 45 = 45 × 2/3 = (45×2)/3 = (15×3×2)/3 = 15×2 = 30
c) 5/4 de 780 = 780 × 5/4 = (780×5)/4 = (195×4×5)/4 = 195×5 = 975
d) 225/100 de 14 = 14 × 225/100 = 14 × 2,25 = 31,5
Ex. 31 :
1) dans la classe B car 4/5 > 3/5
2) dans la classe car B
28 × 3/5 = 16,8 et 25 × 4/5 = 20
Ex. 32 :
1 254 × 2/3 = 836
