Question

Find the p.d across each capacitor is10 micro farads is charged by an 80v supply and then connected across an uncharged 20micro farads capacitors

Answer 1

so, you have an 10 and 20 microfrad inparallel.
Initial charge was q=CV=10*80 microcoulombs=800e-6 coulombs
Now, after the charge the total capacitance is 30 microfarad, so the parallel voltage is V=q/C=800/30=23.3 volts