problem: If a recipe for a two-pound cake requires 1.5 cups of flour, how many cups are needed for 2 five-pound cakes?
solution: We first find that $2$ five-pound cakes results in $2 \times 5 = 10$ pounds of cake total. Since a two-pound cake requires $1.5$ cups of flour, a ten pounds of cake will require five times as much flour (since $10/2=5$). Five times $1.5$ cups of flour is $\boxed{7.5}$ pounds of flour.