Final answer:
The correct absolute value equation for finding the horizontal distance from the left shore where buoys should be placed, considering the river bottom is 20 feet below the surface, is |x| = 20, which is option A.
Step-by-step explanation:
The question involves finding the correct absolute value equation to determine the horizontal distance where buoys should be placed. The absolute value represents the distance from zero on a number line, regardless of direction. Since we know the river bottom is 20 feet below the surface, we're looking for a distance 20 feet away from the point of reference, which is the water's surface. The correct equation must equal a positive 20 because depths and distances are non-negative values.
Option A, |x| = 20, is the correct absolute value equation. Here, x represents the horizontal distance from the left shore, and |x| is the absolute value of x, which gives the non-negative value of x. The equation |x| = 20 signifies that the distance from the left shore could be 20 feet to the right or left, but since we are measuring a depth in a vertical direction, x would be 20, representing a depth of 20 feet below water.