a rendre irréductible svp merci bcp!

A = 354/126
A = 6 x 59 / 6 x 51
A = 59/51

C = 1/4 - 2/7 x 21/8
C = 1/4 - 42/56
C = 1 x 14 / 4 x 14 - 42/56
C = 14/56 - 42/56
C = - 28/56
C = 28 x - 1 / 28 x 2
C = - 1/2