Matt forgot to put the fabric softener in the wash. as his socks tumbled in the dryer, they became charged. if a small piece of lint with a charge of +1.25 e -19 c is attracted to the socks by a force of 3.0 e -9 n, what is the magnitude of the electric field at this location?

I can't remember how to solve this kind of problem.
So, in desperation, I take a hard look at the units.

I do remember that electric field is measured in volts per meter,
and 1 volt/meter means 1 newton/coulomb.  And there it is !
The problem has a quantity of [newtons] and a quantity of [coulombs]
in it.  If I divide those, the quotient will be [newton/coulomb], and THAT's
electric field strength !

                 (3.0 x 10⁻⁹ N) / (1.25 x 10⁻¹⁹ C)
 
             =        2.4 x 10¹⁰  N / C

             =        2.4 x 10¹⁰  volts/meter .