Bonjour
J = 3/9 + 5/18 : (1/4 + 3)
J = 3/9 + 5/18 : [1/4 + (3 x 4) / (1 x 4)]
J = 3/9 + 5/18 : (1/4 + 12/4)
J = 3/9 + 5/18 : 13/4
J = 3/9 + 5/18 x 4/13
J = 3/9 + 20/234
J = (3 x 13) / (9 x 13) + (2 x 10) / (2 x 117)
J = 39/117 + 10/117
J = 49/117
K = 3/5 + 7/10 : 14/5
K = 3/5 + 7/10 x 5/14
K = 3/5 + 35/140
K = 3/5 + (35 x 1) / (35 x 4)
K = 3/5 + 1/4
K = (3 x 4) / (5 x 4) + (1 x 5) / (4 x 5)
K = 12/20 + 5/20
K = 17/20.