58.5 million excess electrons are inside a closed surface. what is the net electric flux through the surface? .

           Net flux through the surface = (net charge inside) / ε₀

and          ε₀ = 8.85 x 10⁻¹² farad/meter.

What's the net charge inside the surface in this problem ?

It's    (5.85 x 10⁷ electrons) x (the charge on each electron)

     =  (5.85 x 10⁷ electrons) x (-1.6 x 10⁻¹⁹ coulomb/electron)

     =      -9.36 x 10⁻¹² coulomb .    

Finally,      (net charge inside) / ε₀ 

             =  (-9.36 x 10⁻¹² coulomb) / (8.85 x 10⁻¹² farad/meter)

             =        -1.058  newton-m²/coulomb .