If the earnings report had been a dud and the stock stayed at or dropped, your option would have expired worthless . Unlike a stock owner who can wait for a recovery, an option buyer has a "ticking clock"—once that expiration date hits, your $600 is gone forever.
Each share in your contract is now worth $20 more than your strike price ($420 - $400).
After subtracting your initial $600 investment, you’ve made a $1,400 profit .