Kayson mixes 300300300 milliliters (\text{mL})(mL)left parenthesis, start text, m, L, end text, right parenthesis of spinach, 200\,\text{mL}200mL200, start text, m, L, end text of berries, and 42\,\text{mL}42mL42, start text, m, L, end text of dressing to make a salad. There are sss milligrams (\text{mg})(mg)left parenthesis, start text, m, g, end text, right parenthesis of vitamin C per milliliter of spinach, b\,\text{mg}bmgb, start text, m, g, end text per milliliter of berries, and d\,\text{mg}dmgd, start text, m, g, end text per milliliter of dressing. Which expressions can we use to describe how many milligrams of vitamin C are in the salad?