bonjour,
A = 2/3 x ( - 7/5) - 9/10
A = - 14/15 - 9/10
A = - 28/30 - 27/30
A = - 55/30
A = - 11 /6
B = 7/6 - 1/6 x 10/7
B = 7/6 - 10/42
B = 49/42 - 10 /42
B = 39/42
B = 13/14
C = - 4/7 x 5/2 - 3 /2 x 7/9
C = - 20/14 - 21/18
C = - 10/7 - 7/6
C = - 60/42 - 49/42
C = - 109/42
D = 3/8 x ( - 2/5 ) + 3/5 x ( - 7/4 )
D = - 6/40 - 21/20
d = - 6 /40 - 42/40
D = - 48/40
D = - 6/ 5
E = - 5/12 x 72/21 - 3/4 x ( 2 + 2 /21 )
E = - 360 /252 - 3 /4 x ( 42/21 + 2/21 )
E = - 360 /252 - 3/4 x 44/21
E = - 10 / 7 - 132/ 84
E = - 10/7 - 11/7
E = - 21 /7
E = - 3
F = ( 5/2 - 1/4) x 5/6 - ( 3 - 7/6)
F = ( 10/4 - 1/4) x 5/6 - ( 18/6 - 7/6)
F = 9/4 x 5/6 - 11/6
F = 45/24 - 11/6
F = 45/24 - 44/24
F = 1 /24