Give the step-by-step reasoning process and then the final answer. If Buzz bought a pizza with 78 slices at a restaurant and then decided to share it with the waiter in the ratio of 5:8, with Buzz's ratio being 5, what's twenty less the number of slices of pizza that the waiter ate?
The total ratio representing the slices of pizza that Buzz bought is 5 + 8 = 13. If he shared the slices of pizza with the waiter, the waiter received a fraction of 8 / 13 of the total number of slices, which totals 8 / 13 * 78 = 48 slices. Twenty less the number of slices of pizza that the waiter ate is 48 - 20 = 28.
The final answer: 28.