Finding Capacitance from Charged Capacitor Energy and Voltage?

[kkingkong]

Capacitor energy problem??

Homework Statement

A capacitor in this device is charged to 6417.0 V and stores 208.0 J of energy. What is its capacitance?

Homework Equations

i know the equation but dnt know how to use it . . C=(kEoA)/d

The Attempt at a Solution

I don't know how to solve this question. i don't even know how to start. please help

 

[lewando]

Try this equation: Energy = (Capacitance*Voltage²)/2