5 pizza / 6 student = 'Z' pizza / 1 student
Cross-multiply the proportion:
5 pizza-student = 6 Z pizza-student
Divide each side of the equation by 6 pizza-student :
5/6 = Z
Each student gets 5/6 of 1 pizza.
It's not so complicated. Cut each pizza into 6 slices,
and each student gets 5 slices.
That's the same as (83 and 1/3) percent of a pizza.