Respostas

2014-03-31T20:14:43-03:00
 -3-(-10)+10-(+15)= 
-3 +10+10-15 = 
+7+10-15 = 
+17 -15 = 
 +2
1 5 1
2014-03-31T20:18:08-03:00
Resposta: -3+10+10-15 = -3+20-15 =-18+20 = +2