Revision test questions

Hello,

I cannot understand the working of the below question:

When a parent acquired 100% of the subsidiary on the 1 January, 2011, the cost of acquisition was $200,000.
In addition, the parent paid legal fees connected with the acquisition of $10,000 and a further $20,000 was payable if the subsidiary achieved profitability in the year ending 31 December, 2012.
(The probability of profitability is looking remote!)
The parent’s cost of capital is 10%.

What is the total cost of acquisition in the calculation of Goodwill (Working 2)?

$216,528
$226,528
$218,182
$210,000
The total cost of acquisition for Working 2 is $216,528 ($200,000 + (.8264 * $20,000))

how the 0.8264 was calculated please?

Thanks