Bonjour,
A = (1-1/7) : 12/5 =
A = (7/7-1/7) : 12/5 =
A = (6/7) : 12/5 =
A = 6/7 * 5/12 =
A = (2*3*5) : (2*2*3*7) =
A = 5 : (2*7) =
A = 5/14
[tex] B=\frac{ \frac{2}{3} + \frac{1}{6} }{2- \frac{1}{2} }= \frac{ \frac{4}{6} + \frac{1}{6} }{ \frac{4}{2}- \frac{1}{2} }=\frac{ \frac{5}{6} }{ \frac{3}{2}}= \frac{5}{6}*\frac{2}{3}= \frac{5}{3}*\frac{1}{3}= \frac{5}{9} [/tex]
ça te vas ?