Best speaker placement

Magfan is exactly right. Your dimensions cause peaks in the bass. Bass traps will help significantly.

Myraj, I've never been a fan of sitting at a wall boundry.
BUT, I think you may be right that it is worth a try, so no beef. I have a small woolen tapestry (Peruvian, bought in mid '80s) on the back wall which tames a nasty echo. I have a short wall setup and the tapestry faces the speakers, over 25' away. I sit no more than 11' away.
I might add that making prescriptive recommendations like these are probably a bad idea, but that the owner in question should start experimenting and reading.
There is a substantial amount of setup 'wisdom' out there and it may even converge on a solution....that is have more in common than major differences.
I am in a tough room, very asymetric with NO symetry whatsoever in a room of basically 26x16 w/ceiling from 9' to 12'.... I recently started experimenting w/my Magnepan 1.6s and moved them closer (close as possible, actually) and realized an instant help. Now, I am slowly messing with toe in. Too much and the image, while solid center also seems to collapse and too little toe and I can get a center gap. I am about to 'break the rules' and swap the speakers L/R and put the tweeters to the INSIDE of the panels. This is a CardinalRule NOT to break w/Maggies but I'm going to do it anyway, since this worked one time, many years ago when I still used MG-1s.
I WILL repeat, however, that rooms of even multiples are 'tough' rooms. No amount of equalization can help a room like the OP's.....all dimensions are a multiple of what is the probable ceiling height....So the room is in the ratio of 1:1.5:3 This is bad juju and will be tough to optomize. Can we agree on that?

Magfan,
The bass tightens up and smooths out at the wall/boundary.
Try it. And you can sit back and just move your head forward (into the dips/peaks) and hear the difference. If it sounds better to your ear, place your seat there.
If it's a tough room, you'll probably like the sound better nearer the rear wall.
Also, you can try hanging something behind your head like a small rug and hear the difference there. If you like it, keep it. Not.....take it down.
Good luck and good listening!

Try this site. It was sent to me a couple months ago and
it did the job. You do have to convert feet to the metric system and fill in all the blanks. You also must choose a speaker close to the design and shape and size of your current speakers. It will provide placement for your speakers. Enjoy!

www.hunecke.de/en/calculators/room-acoustics.html

Myraj,
I was with you up until you put the seat up against the back wall.
Tough room. short wall / long wall?
even multiple room dimmensions will be tough, almost no matter what.
How high is the ceiling? If like 8', (common) than that is another bad. 1.5x is width and 3x is length. This room is a bass monster, I would suspect.

NO benefit by putting the spkrs in the corners....other than lots of exagerated bass.
I'd suggest trying a nearfield placement. Place them across the 24' wall starting with at 7.5' from each side wall, and 3' from the back wall. Put your seat against the rear wall.
Because of your room dimensions being multiples of each other, I predict this to be your best position for the smoothest bass response.
Play with the toe-in adjustment as needed.
Let us know if you try this and how it works for you?
Good luck and good listening!