Réponses

2014-01-10T17:53:35+01:00
25p = 30 (p-2)
25p=30p-60
25p-30p=-60
-5p=-60
p=60/5
p=12
2014-01-10T18:20:45+01:00
25p=30(p-2)
25p=30*p+30*(-2)
25p=30p-60
25p-30p=30p-60-30p
-5p=-60
p=-60/-5
p=12

voilàà :)