Answer
$3.125\times10^{13}$ electrons needs to be removed from the object
Work Step by Step
An object is having charge $q_{i}=-2.0\mu C$
Suppose we removed $q$ charges from this object and finally it is charged as $q_{f}=+3.0\mu C$
$q+q_{f}=q_{i}$
$q=q_{i}-q_{f}$
Thus:
$q=-2.0\mu C-3.0\mu C=-5.0\mu C$
So $-5.0\mu C=-5\times10^{-6}C$ needs to be removed.
$-1.6\times10^{-19}C$ is equal to $1$ electron
$-1C$ is equal to $\frac{1}{1.6\times10^{-19}} $electron
$-5\times10^{-6}C$ is equal to $\frac{5\times10^{-6}}{1.6\times10^{-19}} $electron = $3.125\times10^{13}$ electrons
So $3.125\times10^{13}$ electrons need to be removed from the object
