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Mathematics
Mathematics
Problem
Let
S
=
{
1
,
2
,
3
,
…
,
20
}
S=\{1,2,3,\dots ,20\}
S
=
{
1
,
2
,
3
,
…
,
20
}
and define a relation
R
R
R
on
S
S
S
by
a
R
b
a\,R\,b
a
R
b
if
a
≡
b
(
m
o
d
3
)
a\equiv b\pmod{3}
a
≡
b
(
mod
3
)
. How many elements are there in the equivalence class
[
2
]
[2]
[
2
]
? a) 6 b) 3 c) 7 d) 5
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