Select the correct answer.
Mrs. Smith runs a dessert parlor. Her top-selling items are mixed berry smoothles and milkshakes. She sells mixed berry
smoothles for $5 each and milkshakes for $3 each. Mrs. Smith wants to sell at least 60 mixed berry smoothies and milkshakes in all and
wants to earn at least $210. Each mixed berry smoothle takes 7 minutes to make, and each milkshake takes 3 minutes to make.