Final answer:
The question pertains to Mathematics, with a focus on linear equations and graphing. It involves understanding the slope and y-intercept of a straight line on a graph, represented by the equation y = 3x + 9.
Step-by-step explanation:
The subject of this question is Mathematics, specifically focusing on the algebraic concept of linear equations and graphing in two dimensions. The provided information describes a scenario where a linear graph is used to plot data points, indicating that the value of 'y' changes as a function of 'x'. This change can be visualized on a graph, with the slope representing the rate of change, and the y-intercept providing a starting point when 'x' equals zero.
From FIGURE A1, we can deduce that the line equation based on the slope and y-intercept is y = 3x + 9. Here, 'm' stands for slope, which is 3, indicating a rise of 3 units in the 'y' value for every 1 unit increase in 'x'. The 'b' term represents the y-intercept, which is 9, the point where the line intersects the y-axis.
Graphing linear equations and interpreting their slopes and intercepts is a fundamental concept in algebra that is vital for understanding relationships between variables and is often used in various fields, including physics and economics.