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2010 Stanford Mathematics Tournament
13
13
Part of
2010 Stanford Mathematics Tournament
Problems
(1)
SMT 2010 General #13
Source:
2/11/2012
Find all the integers
x
x
x
in
[
20
,
50
]
[20, 50]
[
20
,
50
]
such that
6
x
+
5
≡
19
m
o
d
10
6x+5\equiv 19 \mod 10
6
x
+
5
≡
19
mod
10
, that is,
10
10
10
divides
(
6
x
+
15
)
+
19
(6x+15)+19
(
6
x
+
15
)
+
19
.
number theory
modular arithmetic