Final answer:
To find the coordinates of point B' after a translation of 8 units down, subtract 8 from the y-coordinate of point B. Without the original coordinates of B, we cannot provide the exact location of B'.
Step-by-step explanation:
To translate a point 8 units down on a coordinate plane means to subtract 8 from the y-coordinate of the point. If point B has coordinates (x, y), then the translated point B′ will have coordinates (x, y - 8). Assume that point B's initial coordinates are not given in this scenario, we just know the operation to perform for the translation.
For example, if point B had coordinates (5, 10), then after translating it 8 units down, point B′ would be at (5, 10 - 8), which simplifies to (5, 2).