This is a system of equations. Let L represent Lucia, and B represent Ben The first equation is: L + B = 150 The second one says that for every dollar ben saved, Lucia saved twice as much. So: L = 2B Now, solve the system 2B + B = 150 3B = 150 B = 50 L = 2(50) L = 100 This means that Ben saved $50, and Lucia saved $100