U= the set of natural numbers between 10 and 20 A= Even numbers B= Multiples of 3 where the number is less than 18. Find (A'UC) - B

Step 1
${\displaystyle U=}$ the set of natural numbers between 10 and 20.
$U=\{11,12,13,14,15,16,17,18,19\}$
${\displaystyle A=}$ even numbers $\Rightarrow \{2,4,6,...18\}$
${\displaystyle B=}$ multiples of three where the number 15 less than 18.
$B=\{3,6,9,12,15\}$
${\displaystyle C=}$ composite numbers
$=\{4,6,8,9,10,12,14,15,16,18,...\}$
Step 2
Find ${\displaystyle \left(A^{\prime }UC\right)-B}$
Hence, $A^{\prime }=\{1,3,5,7,9,11,13,...\}$
Now, $(A^{\prime }UC)=\{1,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,...\}$
and $(A^{\prime }UC)-B=\{1,4,5,7,8,10,11,13,14,16,17,19\}$