The first question's slope is 0 because it is a straight horizontal line
The second question is undefined because it is a straight vertical line
The third question's slope isn't able to be found with a blank line, but the line is positive because the more it travels right, it also goes up. So the slope of the third is positive
The fourth is similar to the third as its slope cannot be calculated with a blank line, but the more it moves right, the more it moves down, meaning the slope is negative.
