We are given
total number of particles =4
and
total sum of charge=-36
Since, all the particles have the same charge
and total charge is negative
so, charge on each particle must be negative
now, we can use formula to find change on each particle
charge on each particle = (total sum of charge)/( total number of particles)
now, we can plug values
and we get
The charge on each particle is
units..............Answer