I am currently doing a Discrete Maths module and one of the questions given was:
Find the number of elements in $\left(A^c \cup B^c\right)^c$ intersection with $C^c$ if the above diagram represents the number of elements in each set
$\cdot^c$ is the complement
The way I understand it is that $A^c \cup B^c$ is just $U$ so $U$ complement intersection with anything should be zero (or phi). But the website says that that answer is incorrect.