We are going to have to divide...
We have to put 1 as a denominator for 3 because it's a whole.
[tex] \frac{1}{2} / \frac{3}{1} [/tex]
Cross multiply.
[tex]1*1=1[/tex]
[tex]3*2=6[/tex]
[tex]= \frac{1}{6} [/tex]
Each person would get [tex] \frac{1}{6} [/tex] of the original pizza.
Have a nice day! :)