Step 1
What is the Universal set U
The universal set is a set that contains all elements including itself.
For this question, the universal set U is
[tex]U=\text{ 500}[/tex]Step 2
Represent this situation by a Venn diagram
Step 3
All the people who visited Paris and Vienna
[tex]\begin{gathered} x\text{ represents the number of people who visited Paris and Vienna only} \\ 75+28+26+22+18+x+7+312=500 \\ 488+x=500 \\ x=\text{ 500-488} \\ x=\text{ 12} \end{gathered}[/tex]Hence, all the people who visited Paris and Vienna is given as
[tex]12+22=\text{ 34}[/tex]Step 4
All the people who visited Paris and Vienna and not London
[tex]\begin{gathered} =34\text{ - 22} \\ =\text{ 12} \end{gathered}[/tex]