Final answer:
To find the value of y in the equation y = 9 + 3x, substitute the given value of x into the equation. The equation represents a straight line with a y-intercept of 9 and a slope of 3, where y changes proportionally with x.
Step-by-step explanation:
To determine the value of y given the equation y = 9 + 3x, you need to have a value for x. If x is known, you can substitute it into the equation to find the corresponding value of y. This linear equation represents a line on a graph with a y-intercept (b term) of 9 and a slope (m term) of 3. Constructing a table of values for different x values and using them to plot points on a graph would show a straight line that the points lie on. Each point corresponds to a solution of the given linear equation. The value of y changes in direct proportion to the value of x, as illustrated by the slope of the line.