The relative frequency is the frequency of the item divided by the total number of all items. The total number of all items here is: 50 + 40 + 90 +20 = 200.
[tex]Burgers = \frac{50}{200} = 25% [/tex]
[tex]Pasta = \frac{40}{200} = 20%[/tex]
[tex]Pizza = \frac{90}{200} = 45% [/tex]
[tex]Salad = \frac{20}{200} = 10% [/tex]
Hope this helps!
