Answer:
r = 1
Step-by-step explanation:
slope = change in y / change in x, so:
change in y / change in x = 2/3
5 - r / 7 - 1 = 2/3
5 - r / 6 = 2/3
![\frac{5-r}{6}=\frac{2}{3}](https://tex.z-dn.net/?f=%5Cfrac%7B5-r%7D%7B6%7D%3D%5Cfrac%7B2%7D%7B3%7D)
now solve this equation.
first, multiply both sides by 6 to get rid of the fraction:
![5 - r = 4](https://tex.z-dn.net/?f=5%20-%20r%20%3D%204)
subtract 5 from both sides
![-r=-1](https://tex.z-dn.net/?f=-r%3D-1)
multiply both sides by -1
![r=1](https://tex.z-dn.net/?f=r%3D1)