bonjour,
A = -90/7 - ( - 9 /35 : 9/7)
⇔ = - 90/7 - ( - 9/35 * 7/9 )
⇔ = - 90/7 - ( - 7/35)
⇔ - 90/7 + 7/35
⇔ - 450/35 + 7 /35
⇔ = - 443/35
B = ( 10/9 + 3 ) : ( - 9/5 - 9 )
⇔ ( 10/9 + 27/9 ) : ( - 9/5 - 45/5)
⇔ 37/9 : - 54/5
⇔ 37/9 * - 5/54
⇔ = - 185/486
C = 10/7 : ( - 6 /13 + 9 /5 )
⇔ 10/7 : ( - 30/65 + 117/65)
⇔ = 10/7 : 87/65
⇔ = 10/7 * 65/87
⇔ 650 /609
