Luce,
You take out $270k from LOC at 5.5%.
You buy a 180 day bank bill for $270,000
At the end of 180 days you sell it for the (maturity) face value of $300,00
You pay back the loan of $270k PLUS $7,425 in interest
You pocket $300k - $270k - $7.425k = $22.575k profit.
The Y-man