Answer:
49
Step-by-step explanation:
By the definition of slope, as vertical change over horizontal change, we get
[tex]-4=m = \frac{\Delta y }{\Delta x} = \frac{r-1}{-6-6} = -\frac{r-1}{12}[/tex]
By checking the first and the last step of that chain
[tex]-4=-\frac {r-1}{12} \rightarrow r-1=48\rightarrow r= 49[/tex]
