Which table of values represents a linear function?

How many quarts of a 50% solution of acid must be added to 20 quarts of a 20% solution of acid in order to get a 40% solution of acid?

Eiko is wearing a magic ring that increases the power of her healing spell by 30%. without the ring, her healing spell restores h health points. which of the following expressions could represent how many health points the spell restores when eiko is wearing the magic ring?

Melody received $140 at the end of a certain week. how many customers did she advise that week?