Respostas

2014-02-09T10:50:19-02:00
3x7=21


9+1+11=21

(n-1)+n+(n+1)=21
3n=21
n=7
n+1=8
n-1=6

1 5 1
2014-02-09T10:52:05-02:00
a) 3.7 = 21
b) 4+7+10 = 21
c) 5+7+9 = 21
2 5 2