Alright, lets get started.
We are asked, what decimal part of 420 is 147.
Lets suppose say x part of 420 is 147.
It means we could write it in equation, so

Dividing 420 in both sides of the equation, so next step would be


x = 0.35
Hence 0.35 decimal part of 420 is 147.
So the answer is 0.35. : Answer
Hope it will help :)