1. The problem is to convert $-20$ microcoulombs ($\mu C$) into coulombs (C). 2. The conversion factor is $1\ \mu C = 10^{-6}\ C$. 3. To convert, multiply the given value by the conversion factor: $$-20\ \mu C \times 10^{-6} = -20 \times 10^{-6}\ C$$ 4. Simplify the multiplication: $$-20 \times 10^{-6} = -2.0 \times 10^{-5}$$ 5. Therefore, $-20$ microcoulombs equals $-2.0 \times 10^{-5}$ coulombs. This means microcoulombs are a millionth of a coulomb, so you multiply by $10^{-6}$ to convert.