Final answer:
The slope of a line parallel to the graph of the equation y = 10x - 20 is 10, as parallel lines have identical slopes.
Step-by-step explanation:
The slope of a line that is parallel to the graph of the equation y = 10x - 20 is the same as the slope of the given equation. In the equation, the coefficient of the variable x, which is 10, represents the slope of the line. Therefore, the slope of any line that is parallel to this line would also be 10.
When we talk about the Algebra of Straight Lines, it is understood that parallel lines will always have the same slope. In the context of the line equation y = mx + b, the m term represents the slope and b represents the y-intercept. According to the figure provided, with a y-intercept of 9 and a slope of 3, we see an example of how the slope dictates how steeply the line rises or falls as one moves along the x-axis.
In conclusion, any line parallel to y = 10x - 20 retains the same steepness, represented numerically by the slope value of 10.