If your LEDs have a max allowed current of 30mA then use 25mA to be safe.
Add the forward voltages of the LEDs (each LED will have a different voltage since the spec'd voltage is a range of voltages) and subtract the total from the supply voltage to have the voltage across the current-limiting resistor, then use simple Ohm's Law to calculate the current-limiting resistor.
Post the datasheet of your LEDs.
Add the forward voltages of the LEDs (each LED will have a different voltage since the spec'd voltage is a range of voltages) and subtract the total from the supply voltage to have the voltage across the current-limiting resistor, then use simple Ohm's Law to calculate the current-limiting resistor.
Post the datasheet of your LEDs.