Réponse :
C = ((24/15 + 35/25) X 20) / 33
= ((8/5 + 7/5) X 20) / 33
= ((15/5) X 20) / 33
= (3 X 20) / 33
= 60/33
= 20/11
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D = (5/6 - 5/4) / (1/2 + 2/3)
= (20/24 - 30/24) / (3/6 + 4/6)
= ( -10/24) / (7/6)
= - ((5/12) / (7/6))
= - ( 5/12 X 6/7)
= - (5/14)
= -5/14