Réponses

2014-09-14T15:34:03+02:00
=64 + (-15)-(-12)-(13-20)
=64 -15 +(+12)-13+(+20)
=49 + 12 - 13 + 20
=61 - 13 + 20
=48+20
=68
2014-09-14T15:34:05+02:00
Bonjour

64 -15 +12 - ( 13-20)
64 -15 +12 - (-7)
64 -15 +12 +7 = 68