Je suis en 4ème qui peut m aider svp Exercices 4 et 7

Bonjour,

.................4/5.................
............A............B..........
.......C........6/5........D.....
4/3.....2/7........E..........F

C = 4/3 x 2/7
C = 8/21

A = 8/21 x 6/5
A = 48/105

E x 2/7 = 6/5
E = 6/5 / 2/7
E = 6/5 x 7/2
E = 21/5

48/105 x B = 4/5
B = 4/5 / 48/105
B = 4/5 x 105/48
B = 105/5 x 4/48
B = 21 x 1/12
B = 21/12
B = 7/4

D x 6/5 = 7/4
D = 7/4 / 6/5
D = 7/4 x 5/6
D = 35/24

21/5 x F = 35/24
F = 35/24 / 21/5
F = 35/24 x 5/21
F = 35/21 x 5/24
F = 5/3 x 5/24
F = 25/72

...........................4/5....................
................48/105.......7/4..........
.........8/21.............6/5..........35/24
....4/3..........2/7.............21/5...........25/72