We took two different approaches to this and they are both correct, except I read the basis number wrong.
In regards to the 300,00, he did not receive it, it went to the buyer, so it is was not realized in regards to the "exchange".
From the perspective of the exchange, his new basis is the old basis plus what he paid in cash; or you can look at it as the 300,000 + 210,000 -22,500. Either way you come up with the same answer.