from typing import Dict


def interpolate_between_points(x0: float, y0: float, x1: float, y1: float, dx: float) -> Dict[float, float]:
    """ Interpolates a line between two points.

    :param x0: The x-coordinate of the first point.
    :param y0: The y-coordinate of the first point.
    :param x1: The x-coordinate of the second point.
    :param y1: The y-coordinate of the second point.
    :param dx: The step size in the interpolation.
    :return: A dict of the interpolated line.
    """
    m = (y1 - y0) / (x1 - x0)
    b = y0 - m * x0
    interpolated = {}

    x = x0
    while x < x1:
        interpolated[x] = m * x + b
        x += dx

    return interpolated