详细讲清楚和倍问题---**Question Stem:** The image displays a system of three mathematical equations written on a green chalkboard-like background. Each equation uses a different combination of three geometric shapes (square, circle, triangle) as variables, representing unknown numbers. The goal is to determine the values represented by each shape. **Equations:** 1. Square (□) + Circle (○) = 7 2. Circle (○) + Triangle (△) = 8 3. Triangle (△) + Square (□) = 9 **Chart/Diagram Description:** * **Type:** This is a representation of a system of linear equations, where geometric shapes act as variables, presented in a visual format on a chalkboard. * **Main Elements:** * **Shapes:** There are three distinct outline shapes: a square (□), a circle (○), and a triangle (△). Each shape is drawn in white. * **Operators:** Standard mathematical addition (+) and equality (=) symbols are used. * **Numbers:** The numbers 7, 8, and 9 are written in a white, handwritten style. * **Layout:** The equations are stacked vertically, with one equation per line. * **Background:** The primary content is presented on a dark green background, resembling a chalkboard. * **Overlay:** A transparent white play button icon (a triangle pointing right within a rounded rectangle) is overlaid near the center of the image, indicating that this is likely a frame from a video. * **Peripheral Elements (not directly part of the problem):** Blurred mathematical expressions and numbers (e.g., "25", "sin²", "29") are visible in the dark blue background surrounding the main green chalkboard area, suggesting a broader mathematical context, but they are not part of the problem itself.