Answer:
See explanation
Step-by-step explanation:
The question is incomplete, as the graph or points of each city are not given.
So, I will provide a general explanation.
To calculate the equation of line through two points;
Start by writing out the coordinates of the two points.
For instance:
![London = (4,6)](https://tex.z-dn.net/?f=London%20%3D%20%284%2C6%29)
![Warsaw = (20,10)](https://tex.z-dn.net/?f=Warsaw%20%3D%20%2820%2C10%29)
This points will be represented as:
![(x_1,y_1) = (4,6)](https://tex.z-dn.net/?f=%28x_1%2Cy_1%29%20%3D%20%284%2C6%29)
![(x_2,y_2) = (20,10)](https://tex.z-dn.net/?f=%28x_2%2Cy_2%29%20%3D%20%2820%2C10%29)
Calculate the slope (m)
![m = \frac{y_2 - y_1}{x_2 -x_1}](https://tex.z-dn.net/?f=m%20%3D%20%5Cfrac%7By_2%20-%20y_1%7D%7Bx_2%20-x_1%7D)
![m = \frac{10 - 6}{20 - 4}](https://tex.z-dn.net/?f=m%20%3D%20%5Cfrac%7B10%20-%206%7D%7B20%20-%204%7D)
![m = \frac{4}{16}](https://tex.z-dn.net/?f=m%20%3D%20%5Cfrac%7B4%7D%7B16%7D)
Simplify
![m = \frac{1}{4}](https://tex.z-dn.net/?f=m%20%3D%20%5Cfrac%7B1%7D%7B4%7D)
The equation is then calculated as:
![y = m(x - x_1) + y_1](https://tex.z-dn.net/?f=y%20%3D%20m%28x%20-%20x_1%29%20%2B%20y_1)
This gives:
![y = \frac{1}{4}(x - 4) + 6](https://tex.z-dn.net/?f=y%20%3D%20%5Cfrac%7B1%7D%7B4%7D%28x%20-%204%29%20%2B%206)
Open bracket
![y = \frac{1}{4}x - 1 + 6](https://tex.z-dn.net/?f=y%20%3D%20%5Cfrac%7B1%7D%7B4%7Dx%20-%201%20%2B%206)
![y = \frac{1}{4}x +5](https://tex.z-dn.net/?f=y%20%3D%20%5Cfrac%7B1%7D%7B4%7Dx%20%2B5)
<em>Apply the above steps in the original question</em>