Answer:
-1
Step-by-step explanation:
If a straight line passes through the known points (x1, y1) and (x2, y2), the its slope is given by [tex] m = \frac{y1-y2}{x1-x2}[/tex]
Now, in our case the straight line passes through the points (1.8, - 3.4) and (6.8, - 8.4).
Therefore, the slope of the required straight line will be [tex] m = \frac{-3.4-(-8.4)}{1.8-6.8}= -1[/tex] ( Answer )