Travelling in the Nether

Solution 1:

First thing that we need to do is convert chunk coordinates into block coordinates. Easy way to do this is multiply coordinates by 16.

House chunk contains blocks (272,y,480) to (287,y,495)

Mansion chunk contains blocks (-3232,y,11968) to (-3217,y,11983)

We will say house is (280,y,485) and mansion is (-3225,y,11975)

Nether coordinates are overworld coordinates divided by 8.

House would be (35,y,60 nether) and mansion would be (-403,y,1496 nether).

If you are going from nether coordinates to overworld coordinates, multiply by 8.

If you need exact position portals, one method is to build the overworld portal where you want it, do the math on the overworld coordinates, and enter the portal. If the nether portal location is not good, destroy it. Build a new nether portal in the coordinates you calculated at a higher or lower level. Then you just have to verify that you can pass through the portals in both directions without creating a third portal in a weird location.

If you don't have any other portals in the area, you can get away with some deviation from exact coordinates. When you enter a portal, it searches anything within 128 blocks from the player in the destination world. Your destination will be the closest portal it finds.

I generally build portals at the very top of the nether just below bedrock. There aren't as many caverns or large lava lakes so I can dig highways to my destinations.

If you need several portals in close proximity, like a town with friends and everyone wants their own, stick to exact coordinates. The build technique is a little different too. After you have the first working portal set, for the rest of the portals, you want to hand build both the overworld and the nether portal in their exact coordinates. Otherwise you can end up at someone else's portal. You can have portal sets very close to each other using this technique.

Here is the wiki for everything you ever wanted to know about nether portals.

Just for fun, I decided to test how close I could put portals and have them exit the portal I wanted. You can get them back to back.

Here are the two overworld portals:

Here are the nether portals:

Solution 2:

Travel by default is 8x shorter in the Nether. So, if you are going from 17 to -202 that is a distance of 219 overworld blocks. Divide by 8 and you have to only go about 27 blocks in the Nether.

Which...is...not worth going to the nether since you won't even be able to get two functional portal endpoints that close together anyway.

So, while I think your numbers may be a bit smallish for the example, apply that logic to your distance calculations and you should be able to figure out where you need to go in the Nether to get to someplace in the overworld.