Interactive Geometric–Algebra Demo for Simple Interest

This example demonstrates a dynamic simple-interest calculator where users input principal, interest rate, and time to see how the interest amount is computed and displayed with interactive labels. It focuses on the simple interest model (e.g., I = P·r·t, using equivalent variable forms) and the underlying algebraic structure: substitution of parameters and multiplication-based dependence. Construction uses GeoGebra text inputs (Textfield) for parameters such as P, R, and T (via InputBox1–InputBox3) and multiple Text objects (text1–text6 and additional text fields) to present the computed values and relationships. Interactive controls (button1–button3) support updating the display. Suitable for middle school through introductory college coursework, especially for finance-math intuition and modeling with basic functions and parameterized expressions.