Interactive example: add a number to two numbers to reach a target sum

This example demonstrates how to satisfy an arithmetic constraint: given two numbers a and b and a target c, find an additional number ans such that a + b + ans = c. It visualizes the idea of solving for an unknown from a simple equation and immediately checks whether the entered value meets the required result. The key concepts are arithmetic equations, variable isolation (ans = c − a − b), and dynamic feedback using interactive controls. Construction (from the provided GeoGebra summary): Random is used to generate the problem data (e.g., a, b, c); Textfield together with an input component like InputBox1 lets users enter or adjust ans; sum computes a + b as an intermediate quantity; multiple text objects (text1–text5) display the step-by-step values and the final verification; button1 triggers recalculation/refreshing so the displayed texts update accordingly. Suitable for primary and middle school learners and for classroom interactive exercises or introductory modeling activities.