Answer:
6/7
Step-by-step explanation:
Your first step will be to find the slope of Line C. Using the slope formula of [tex]\frac{y_{2}-y_1 }{x_2-x_1}[/tex], the slope of Line C is [tex]\frac{7-14}{7-1} = \frac{-7}{6}[/tex].
If Line D is perpendicular to C, that means the slope is the negative reciprocal of Line C. So, that means the slope is 6/7.