Kayson mixes 300milliliters (mL) of spinach,200mL of berries, and 42mL of dressing to make a salad. There are s milligrams (mg) of vitamin C per milliliter of spinach, b mg per milliliter of berries, and d mg per milliliter of dressing.Which expressions can we use to describe how many milligrams of vitamin C are in the salad?