A=1/3-1/3x4/7   B=6/5:(1/15-1/5) a) CALCULER a ET ECRIRE LA REPONSE SOUS LA FORME D UNE FRACTION IRREDUCTIBLE b) CALCULEZ b ET ECRIRE LA REPONSE SOUS LA FORME D

a)
A = 1/3 - 1/3 x 4/7
A = 1/3 - 4/21
A = 1 x 7 / 3 x 7 - 4/21
A = 7/21 - 4/21
A = 3/21
A = 3 x 1 / 3 x 7
A = 1/7

b)
B = 6/5 : (1/15 - 1/5)
B = 6/5 : (1/15 - 1 x 3 / 5 x 3)
B = 6/5 : (1/15 - 3/15)
B = 6/5 : - 2/15
B = 6/5 x - 15/2
B = - 90/10
B = 10 x - 9 / 10 x 1
B = - 9