Final answer:
The y-intercept of the line with a slope of 1/3 and an x-intercept of -9 is 3.
Step-by-step explanation:
To find the y-intercept of a line given its slope (m) and x-intercept, we can use the slope-intercept form of a linear equation, which is y = mx + b, where m is the slope and b is the y-intercept. We know the slope (m) is 1/3, and the line crosses the x-axis at x = -9 (x-intercept). When a line crosses the x-axis, the y-value is 0. Plugging these values into the equation gives us 0 = (1/3)(-9) + b, which simplifies to 0 = -3 + b. To find b, we add 3 to both sides of the equation to get b = 3, which is the y-intercept.