fractions 3ème calcul et résultat fraction à simplifier merci

J = (1/8 - 7/12) : (7/6 + 7/16)
J = (1 x 3 / 8 x 3 - 7 x 2 / 12 x 2) : (7 x 8 / 6 x 8 + 7 x 3 / 16 x 3)
J = (3/24 - 14/24) : (56/48 + 21/48)
J = - 11/24 : 77/48
J = - 11/24 x 48/77
J = - 528/1848
J = 264 x - 2 / 264 x 7
J = - 2//7

K = 1/8 - 7/12 : 7/6 + 7/12
K = 1/8 - 7/12 x 6/7 + 7/12
K = 1/8 - 42/84 + 7/12
K = 1 x 21 / 8 x 21 - 42 x 2 / 84 x 2 + 7 x 14 / 12 x 14
K = 21/168 - 84/168 + 98/168
K = 35/168
K = 7 x 5 / 7 x 24
K = 5/24

M = 1/8 + 7/12
      5/6 - 4/15
M = 1 x 3 / 8 x 3 + 7 x 2 / 12 x 2
      5 x 5 / 6 x 5 - 4 x 2 / 15 x 2
M = 3/24 + 14/24
      25/30 - 8/30
M = 17/24 : 17/30
M = 17/24 x 30/17
M = 510/408
M = 102 x 5 / 102 x 4
M = 5/4

N = 5/3 - 7/9
     1/4 - 1/2
N = 5 x 3 / 3 x 3 - 7/9
     1/4 - 1 x 2 / 2 x 2
N = 15/9 - 7/9
      1/4 - 2/4
N = 8/9 : - 1/4
N = 8/9 x - 4
N = - 32/9

P =      1/5__
       6 - 4/15
P =                 1/5_____
      6 x 15 / 1 x 15 - 4/15
P =     1/5_____
    90/15 - 4/15
P = 1/5 : 86/15
P = 1/5 x 15/86
P = 15/430
P = 5 x 3 / 5 x 86
P = 3/86