Problems and exercises involving different subjects at the same time at the undergraduate level

Question

I know that at the research level, it's common to use different areas of Mathematics to solve a problem. But my question is whether at the undergraduate level it is possible to have a problem or exercise in which to solve it, it is necessary to use subjects that are not normally seen together. For example, a problem involving at the same time Differential Geometry and Differential Equations, or Abstract Algebra and Calculus or Linear Algebra and Combinatorics... In short, is this possible? Could someone give me examples ? PS: I'm not talking about subjects that are pre-requisite to each other like Analytic Geometry and Calculus. And remember, I'm referring to the undergraduate level.