C’est pour demain merci. J’ai besoin que des deux derniers ( C & D ).

C = 8/3 - 5/7 : 20/21
C = 8/3 - 5/7 x 21/20
C = 8/3 - 105/140
C = 8 x 140 / 3 x 140 - 105 x 3 / 140 x 3
C = 1120/420 - 315/420
C = 805/420
C = 35 x 23 / 35 x 12
C = 23/12

D = 1/7 + 6/5 : 12/35
D = 1/7 + 6/5 x 35/12
D = 1/7 + 210/60
D = 1 x 60 / 7 x 60 + 210 x 7 / 60 x 7
D = 60/420 + 1470/420
D = 1530/420
D = 30 x 51 / 30 x 14
D = 51/14