Correction of errors (IAS 8)

Apologies Mr. Little, i know these topics are supposed to be self study but i just couldn’t get it.

Question : During 20X7 Philips Petroleum discovered that certain items had been included in inventory as at 31 Dec 20X6, valued at $4.2 million, which had been in fact sold before the year end.

20X6 20×7(Draft)
(millions) (millions)
sales 47400 67200
cost of goods sold (34,570) (55800)
profit before tax 12830 11400
income taxes (3,880) (3400)
profit for the period 8950 8000

Retained earnings at 1 January 20X7 were $13 million. The cost of goods sold for 20X7 includes the $4.2 million error in opening inventory. The income tax rate was 30% for 20X6 and 20X7.

Required : Show the income statement for 20X7, with 20X6 comparative.

Workings
cost of goods sold (20X6) 34570 +4200=38770

Workings
income tax (20X6)
As stated in question 3880
Inventory adjustment (4200 x 30%) (1260)
correct income tax for 20X6 2620

My question Mr.Little : I do not understand how they came to the correct tax figure for 20X6, which is $2620. What i did was this:
After getting the correct cost of sales(38770) i subtracted it from the sales figure for 20X6 to get a profit of $8,630,000. I then taxed this amount at a rate of 30%, getting a tax figure of $2,589,000. Apparently this is wrong and i can’t figure out why. Your assistance would be greatly appreciated Mr. Little.