The order in which the food is selected does not matter.

For a three item lunch, how many items are there to choose from and how many are you going to select?

₆C₃

Now find how many lunches of two items can be selected.

2 · ₆C₂

Now find how many lunches of one item can be selected.

₆C₁

₆C₃ + 2 · ₆C₂ + ₆C₁ = 20 + 2(15) + 6 = 56