How do animators draw graphics at same place in each frame? Take the example of older days when computer graphics didn't exist like Tom and jerry in 50s or hand drawn animation in Paper Flipbook in modern times .

see https://img-9gag-fun.9cache.com/photo/aV3M8NK_460sv.mp4 for example 

How are animators able to draw the same image in same proportions at same spot over several frames almost flawlessly?

clearly without any aid its not possible to draw the same object on each frame at same place and with correct size and color as the last frame.

how do they accomplish this?
There may be a number of techniques used: 
Traditional animations had a complex workflow involving hand-coloured xerographed outlines. Backgrounds were drawn separately and reused (even in multiple films), and individual frames weren't all drawn by the same people.

A quote from the first link is instructive:


  A peg bar is an animation tool used in traditional (cel) animation to keep the drawings in place. The pins in the peg bar match the holes in the paper. It is attached to the animation desk or light table, depending on which is being used. 


A hand-made flipbook could just use a makeshift lightbox with a master outline fixed under individual pages held on pegs or even taped into a precise position.

(All links wikipedia, the first in particular is an interesting read)