Bonjour
A = 7/2 + 9/7 : 1/14
A = 7/2 + 9/7 x 14
A = 7/2 + 126/7
A = (7 x 7) / (2 x 7) + (126 x 2) / (7 x 2)
A = 49/14 + 252/14
A = 301/2
B = - 9/13 : - 1/30 x - 13/17
B = - 9/13 x - 30 x - 13/17
B = 270/13 x - 13/17
B = - 3 510/221
B = (13 x - 270) / (13 x 17
B = - 270/17
C = - 2/9 + 13/3 - - 5/18
C = (- 2 x 2) / (9 x 2) + (13 x 6) / (3 x 6) + 5/18
C = - 4/18 + 78/18 + 5/18
C = 79/18
D = - 3/20 + 6/31 : - 1/31
D = - 3/20 + 6/31 x - 31
D = - 3/20 - 186/31
D = - 3/20 - 6
D = - 3/20 - (6 x 20) / (1 x 20)
D = - 3/20 - 120/20
D = - 123/20