The set S represents odd numbers to 31.
S = {1, 3, 5, 7, 9, 11, 13, 15, 17, 21, 23, 25, 27, 29, 31}

The set C represents multiples of 5 to 30.
C = {5, 10, 15, 20, 25, 30}

How many elements are in the set S u C

Question

The set S represents odd numbers to 31.
S = {1, 3, 5, 7, 9, 11, 13, 15, 17, 21, 23, 25, 27, 29, 31}

The set C represents multiples of 5 to 30.
C = {5, 10, 15, 20, 25, 30}

How many elements are in the set S u C

anonymous · Answer

is it 19?

anonymous · Answer

i thought amistre just told me that the U means all of them ... im confuzzled

hoblos · Answer

yes yes but you must not repeat the common elements
you have 3 elements in common ( 5,15&25)
in S there are 15 elements
in C there are 6 elements
their sum is 21 elements 
so in  S u C we have 21-3 = 18 elements