how does the electric force between two charged particles change if one particle's charge is reduce by a factor of 3

It is decreased by a factor of 4.

Explanation:

if one of the charge is doubled, the electric potential energy would be doubled too.

step-by-step explanation:

we are given

we have to simplify it

firstly, we will factor it

now, we can cancel like terms

now, we can combine it

so, we get