Can anyone help and explain how they got the answer?

Question

quantity of pizza slices- 0 1 2 3 4 5

Total utility of pizza- 0 25 43 _ _ _

Marginal Utility of pizza _ _ _ 11 5 -1

Answer 1

quantity of pizza slices- 0 1 2 3 4 5

Total utility of pizza- 0 25 43 54 59 58

Marginal Utility of pizza x 25 18 11 5 -1

..0...1....2....3 ...4....5

..0..25..43..54 ..59..58

......25..18..11 ...5...-1

You have total utility line 0 25 43 _ _ _

so check marginal utility - each one gives extra to total utility so 43+11=54 now it becomes 0 25 43 54 _ _

next 54+5=59  now it becomes 0 25 43 54 59 _

next 59 - 1=58 now it becomes 0 25 43 54 59 58

Opposite way marginal utility line: _ _ _ 11 5 -1

Total utility changes from 0 to 25, so 25-0=25

now it becomes X 25 _ 11 5 -1

next 43-25=18

now it becomes X 25 18 11 5 -1

X means that there no any marginal utility for zero quantity of pizza.