Final answer:
Using the slope formula, m = (y2 - y1) / (x2 - x1), with the given slope of 3 and points (6,r) and (8,2), we find that the missing coordinate r = -4, which doesn't match any of the provided answer choices.
Step-by-step explanation:
To find the missing coordinate r for the point (6,r), we use the fact that the slope (m) of the line passing through two points (x1, y1) and (x2, y2) is given by (y2 - y1) / (x2 - x1). Given that the slope of our line is 3 and it passes through (6,r) and (8,2), we set up the slope equation as follows:
3 = (2 - r) / (8 - 6)
3 = (2 - r) / 2
To solve for r, multiply both sides by 2 and add r to both sides:
6 = 2 - r
r = -4
Therefore, as none of the given answer choices match -4, it seems there might be an error with the question or the answer choices given.