Question

What does Q represent in the formula for capacitance?

Answer 1

In this problem, I know it is solved with
$$C=\frac{Q}{ΔV}$$
But why is
$$ Q=12μC $$?

Shouldn't it be
$$Q=|q1||q2|=144μC$$?

Answer 2

I looked it up and figure it out. Each conductor must have equal charge, thus you only use $$Q = +12\mu C$$