Voltage Changes

[Xtra_Zero]

Ok.  So I need to run a set of 4 LEDs off the 12v DC 3.25 Amp Gamecube power supply.  This would be alot more straightforward if the LEDs were the same voltage.  Well.. They aren't.  I need to run the set of LEDs in this order:

1.7v, 20 mA  ->  3.7v, 20 mA  ->  2.1v, 20 mA  ->  2.1v, 30 mA

I'm a little inexperienced in the resistor department, and am not sure how I should go about calculating this out...

[viletim!]

read about kirchoff's current law