Charge after three time constants?

[Keeeen]

Homework Statement

A 10V supple is connected to a 2.2μF capacitor in series with a 10kΩ resistor. To what value will it have charged after three time constants?

Homework Equations

I know that T=RC but I have no idea beyond this point

The Attempt at a Solution

T=RC
T=2.2μF*10kΩ
T=22

the rest is unknown to me, if someone could explain it to me that would be awesome.

 

[rude man]

Either find the expression for a charging capacitor or derive it yourself. It's a simple linear, first-order, constant-coefficient differential equation. (Sum currents to zero at the capacitor-resistor junction.)