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National and Regional Contests
Paraguay Contests
Paraguay Mathematical Olympiad
2007 Paraguay Mathematical Olympiad
4
4
Part of
2007 Paraguay Mathematical Olympiad
Problems
(1)
Paraguayan National Olympiad 2007, Level 3, Problem 4
Source:
9/1/2014
Each number from the set
{
1
,
2
,
3
,
4
,
5
,
6
,
7
}
\{1, 2, 3, 4, 5, 6, 7\}
{
1
,
2
,
3
,
4
,
5
,
6
,
7
}
must be written in each circle of the diagram, so that the sum of any three aligned numbers is the same (e.g.,
A
+
D
+
E
=
D
+
C
+
B
A+D+E = D+C+B
A
+
D
+
E
=
D
+
C
+
B
). What number cannot be placed on the circle
E
E
E
?