Bonjour,

A = 2 + 8

       9 + 5/19

A = 2 + 8 : [(9 x 19) / (1 x 19) + 5/19]

A = 2 + 8 : (171/19 + 5/19)

A = 2 + 8 : 176/19

A = 2 + 8 x 19/176

A = 2 + 152/176

A = (2 x 22) / (1 x 22) + (8 x 19) / (8 x 22)

A = 44/22 + 19/22

A = 63/22

B = 1 + 1/8 + 3/4 - 1/12

          5/6 + 1/3 + 2

B = 1 + [(1 x 3) / (8 x 3) + (3 x 6) / (4 x 6) - (1 x 2) / (12 x 2)]

                5/6 + (1 x 2) / (3 x 2) + (2 x 6) / (1 x 6)

B = 1 + 3/24 + 18/24 - 2/24

            5/6 + 2/6 + 12/6

B = 1 + 19/24 : 19/6

B = 1 + 19/24 x 6/19

B = 1 + 114/456

B = (1 x 4) / (1 x 4) + (114 x 1) / (114 x 4)

B = 4/4 + 1/4

B = 5/4

C =      5/12

   7/3 x 8/15 - 5/6

C =      5/12

     56/45 - 5/6

C =                    5/12_______

(56 x 6) / (45 x 6) - (5 x 45) / (6 x 45)

C =       5/12

336/270 - 225/270

C = 5/12 : 111/270

C = 5/12 x 270/111

C = 1350/1332

C = (18 x 75) / (18 x 74)

C = 75/74.