Réponses

2014-01-22T17:23:58+01:00
1) 
=7/15 -(2*3*3)/(5*3*2*2)
=7/15 - 3/(5*2)
=(7*10)/(15*10) - (3*15)/(10*15)
=70/150 - 45/150
=25/150
=1/6