How do I use i(t) = c^(dv(t)/dt) and c=q/v and
Those capacitors are in parallel, not series. Whenever you have capacitors in parallel, the total effective capacitance is just the arithmetic sum.


The charge on the 2F capacitor can be calculated using the equation Q=CV. Where C=2F and V=9V because voltages across parallel branches are equal. Thus $$Q_{2F}=18C$$
The total charge can be found using the same equation. Where C=10F which is the total effective capacitance and V=9V. Thus $$Q_{total}=90C$$
Again, total effective capacitance for parallel capacitors is just arithmetic sum. Thus $$C_{total}=10F$$