The slope of a line is the ratio of the change in the y-coordinate to the change in the x-coordinate. In this case, the slope of the line passing through the points (0,0) and (6,6) is positive because as the x-coordinate increases from 0 to 6, the y-coordinate also increases from 0 to 6. This means that as one variable increases, the other variable also increases, leading to a positive slope.
