I think they way they set the price is to take the number of shares available, subtract out the number for which there are market orders (i.e. orders to buy at the market price, i.e. non-limit orders), then take the remaining shares and the open limit orders, and find the highest price that gets all the shares sold.

So if it opened at $85, that means there were limit orders placed at that level and higher.

I don't know why there was a delay in the price reporting.