24V supply run 12V 3014 LED strip in series; help with resistors for series
Assuming that your strips are designed to operate at 12V and 30mA, comprising 3 series LEDs and a current limiting resistor, you probably don't need to add another resistor.

If the 12V strings are well matched, meaning that they draw the same current when 12V is applied to them, then you can simply connect two strips in series and apply 24V. Connect the negative end of strip "A" to the positive end of strip "B"; connect your 24V supply to the positive end of strip "A" and the negative end of strip "B".

Putting two 12V strips in series effectively gives you a single 24V strip with the same current demand. So, your 150mA power supply should be able to drive 5 such strips but you would be operating the supply right at its specified maximum current.