Respostas

2013-11-12T16:22:26-02:00
-7/15+1/6       mmc de 15 e 6=30
-14/30+5/30= -9/30 ( Simplificando)
-3/10

2013-11-12T16:25:24-02:00
(-7/15)= +ou-  -0,466...   (+1/6)=+ou-0,166...
+ou-0,466...+ +ou- -0,166...= +ou- -0,632