This process goes with:
5 + 0.8x = 36 ~ Subtract both sides by 5.
0.8x = 31 ~ Divide both sides by 0.8.
x = 38.3 ~ Roughly 38, considering that it doesn't round off to completely covering 36 miles then the answer would be it would take 39 weeks.
Answer: 39 Weeks.
I hope that helps, have a great rest of your day! ^ ^
~Ghostgate