bonjour
A = - 2/5 : 3/15 + 2/15
A = - 2/5 x 15/3 + 2/15
A = - 30/15 + 2/15
A = - 28/15
B = 9/2 - 5/2 : 15/8
B = 9/2 - 5/2 x 8/15
B = 9/2 - 40/30
B = 9/2 - 4/3
B = 27/6 - 8/6
B = 19/6
A = 7/6 - 5/4 x 1/2
A = 7/6 - 5/8
A = 28/24 - 15/24
A = 13 /24
B = 5/9 : ( 5/9 + 1/6 )
B = 5/9 : ( 10/18 + 3/18 )
B = 5/9 ; 13/18
B = 5/9 x 18/13
B = 90/117
B = 10/13