Marla noticed that her friend Ron had three times as many pieces of candy as she did. She told him, "If you give me seven pieces
of your candy, we'll have exactly the same number of pieces." Ron responded, "I didn't know that until you mentioned it. But I'll make you a deal: If you can show me how to solve this puzzle using algebra, I'll give you the seven pieces. "One minute later, Ron was shocked to see that Marla had solved it perfectly. Can you do the same?