Step 1: Find the slope:

This gives you
, but we need to find b.
To find b, substitute in one (x,y) pair and it doesn't matter which one. I'll go with (4,-2):
![\begin{aligned}-2&=-\dfrac{3}{2}(4)+b\\[0.5em]-2&=-6+b\\[0.5em]4&=b\end{aligned}](https://tex.z-dn.net/?f=%5Cbegin%7Baligned%7D-2%26%3D-%5Cdfrac%7B3%7D%7B2%7D%284%29%2Bb%5C%5C%5B0.5em%5D-2%26%3D-6%2Bb%5C%5C%5B0.5em%5D4%26%3Db%5Cend%7Baligned%7D)
Now take that b-value and plug in into the slope-intercept form:

It's always a good idea to toss in the other x-value from the other point, to make sure it checks out.
Answer:
C
Step-by-step explanation:
Now, what we know is that the total distance from the dormitory to the city is 1 if expressed in fraction. What we need to know is the fraction of the journey that is scheduled as the last part.
We can get this by subtracting the fractions of the first two phases from 1.
This goes as follows:
1 - (1/5) - (2/3) = 2/15
Now, we know that the final 8 kilometers constitute a fraction of just 2/5
Hence, we know that 2/15 of the total journey is 8 kilometers.
Let the total journey distance be T. This means that 2/15 of T is 8km
2/15 * T = 8km
T = ( 8 * 15 )/2 = 120/2 = 60km
Hmmm A millimeter would be too big for that .
I think millionths of a meter would be about right. Micrometers.