Answer
$q=-1.32\times10^{13} C$
Work Step by Step
We know that
$q=-ne ..........eq (1)$ the negative sign indicates that the charge on electrons is negative
$n= \frac{m}{m_e}$ where 'm' is given mass and '$m_e$' is the mass of an electron
So: $n=\frac{75}{9.11\times10^{-31}}=8.23\times10^{31}$
Plugging in the known values, we obtain:
$q=-8.23\times10^{31}\times1.6\times10^{-19}$
$q=-1.32\times10^{13} C$
