Bob has half as many quarters as dimes. He has $3.60. How many of each coin does he have? Let q be the number of quarters. Let d be the number of dimes. We're given: q = 0.5d 0.25q + 0.10d = 3.60 Substitute (1) into (2): 0.25(0.5d) + 0.10d = 3.60 0.125d + 0.1d = 3.6 Combine like terms: 0.225d = 3.6 Typing this equation into our search engine, we're given: d = 16 Substitute d = 16 into Equation (1): q = 0.5(16) q = 8