Can you specify the page in the CFAI curriculum for this?
I have the same idea with you. Since the COGS FIFO= COGS LIFO - changes in LIFO reserve. It is logical to calculate the NI FIFO = NI LIFO +changes in LIFO reserve * (1 - tax rate).
The solution is correct. The key here is that there is a LIFO liquidation, so when you subtract the change you end up adding it back on (which makes sense since you are selling older and cheaper inventory at today’s higher prices and therefore profit should be higher)
The change in LIFO reserve is -4000 which means FIFOcogs are 4000 higher than LIFOcogs (due to the double negative). Taking into account the tax impact means that Net Profit will be 4000*(0.69) lower due to the higher COGs which gives you the answer of 9240.
It looks like they may have labelled the 2012 and 2013 reserve numbers the wrong way around.