def y_intercept_line(slope, point):
    """
    Calculate a y-intercept of a line for given values of slope and point.

    Parameters
    ----------
    slope : float
        A value of slope line.
    point : tuple
        A tuple with xy coordinates.

    Returns
    -------
    y-intercept : float
        A vaule of the y-intercept for the line.
    """
    return point[1] - slope*point[0]